Previous Article | Next Article 
Applied and Environmental Microbiology, December 2000, p. 5221-5225, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Control of Expression of Divergent
Pseudomonas putida put Promoters for Proline
Catabolism
Susana
Vílchez,
Maximino
Manzanera, and
Juan
L.
Ramos*
Departments of Plant Biochemistry and
Molecular and Cellular Biology, Estación Experimental del
Zaidín, Consejo Superior de Investigaciones
Científicas, E-18008 Granada, Spain
Received 22 May 2000/Accepted 25 September 2000
 |
ABSTRACT |
Pseudomonas putida KT2440 uses proline as the sole C
and N source. Utilization of this amino acid involves its uptake, which is mediated by the PutP protein, and its conversion into glutamate, mediated by the PutA protein. Sequence analysis revealed that the
putA and putP genes are transcribed
divergently. Expression from the putP and putA
genes was analyzed at the mRNA level in different host backgrounds in
the absence and presence of proline. Expression from the
put promoters was induced by proline. The transcription
initiation points of the putP and putA genes
were precisely mapped via primer extension, and sequence analysis of the upstream DNA region showed well-separated promoters for these two
genes. The PutA protein acts as a repressor of put gene
expression in P. putida because expression from the
put promoters is constitutive in a host background with a
knockout putA gene. This regulatory activity is independent
of the catabolic activity of PutA, because we show that a point
mutation (Glu896
Lys) that prevents catalytic activity allowed the
protein to retain its regulatory activity. Expression from the
put promoters in the presence of proline in a
putA-proficient background requires a positive regulatory
protein, still unidentified, whose expression seems to be
54 dependent because the put genes were not
expressed in a 54-deficient background. Expression of
the putA and putP genes was equally high in the
presence of proline in 38- and ihf-deficient
P. putida backgrounds.
| |
INTRODUCTION |
Pseudomonas putida mt-2
is a saprophytic soil bacterium able to use m-methylbenzoate
as the sole C source (34). This strain and its DNA
restriction-deficient mutant called KT2440 have been shown to be
aggressive root colonizers and are considered rhizosphere microorganisms (23).
Recent studies have focused on the possible role of amino acids as
alternative carbon substrates that can support the growth of
microorganisms in the rhizosphere of plants (9, 15, 29, 35).
All of the 20 amino acids present in the proteins can be detected in
plant exudates. Our group and others have shown that proline is one of
the most abundant amino acids in corn root exudates (31,
32); therefore, this amino acid could be an important energy
source for bacteria during the first stages of colonization of plant roots.
We have found that P. putida KT2440 can use proline as the
sole C and N source, and we have recently cloned the genes of P. putida involved in proline utilization (named put for
proline utilization) (32). In enteric bacteria and P. putida (2, 17, 19, 32), two genes were found to be
essential for proline metabolism: the putP gene, whose gene
product is involved in the uptake of proline to the cytoplasm of the
cell, and the putA gene product, a multifunctional protein
that not only catalyzes the formation of glutamate from proline via
pyrroline-5'-carboxylic acid but is also involved in control of
expression of the put genes (24-27). The
putA gene has also been identified in Rhodobacter and Agrobacterium species and members of the family
Rhizobiaceae (8, 11, 12, 14).
Using the transcriptional fusions of the putA and
putP promoters to 'lacZ, it was shown that the
putA and putP genes are regulated at the
transcriptional level in P. putida, with proline acting as
an inducer, since 
-galactosidase levels from the putA and putP gene promoters increased by about 20- and 4-fold,
respectively, in liquid culture medium in the presence of proline
(32). However, the promoter regions of these genes and their
pattern of expression are unknown. Using the put promoter
fusions to 'lacZ, it was shown that in a putA
mutant background, high levels of expression from these genes occurred,
suggesting that the P. putida PutA protein acts as a
repressor of putA and putP gene expression, as
also described for enteric bacteria (27) and
Rhodobacter capsulatus (14). In enteric bacteria,
in addition to the putA gene, two other host factors,
integration host factor (IHF) and 54, are involved in
control of expression of the put genes (4, 26,
27). rpoN and ihfA mutants of P. putida KT2440 deficient in the synthesis of 54 and
IHF, respectively, are available; however, the patterns of expression
of the put genes in these backgrounds are unknown.
In this study we analyzed expression from the put promoters
at the mRNA level in different P. putida backgrounds in the
absence and presence of proline, and we describe a plausible model for the control of expression of the proline utilization genes in P. putida. We also report that the regulatory activity of the P. putida PutA protein is independent of the catabolic
activities of this multifunctional protein.
| |
MATERIALS AND METHODS |
Bacterial strains and culture conditions.
The P. putida strains used in this study are shown in Table
1. P. putida KT2440-Pro21 is a
spontaneous mutant unable to use proline as the sole C and N source. It
has a point mutation that causes Glu-896 to be replaced by Lys in the
translated protein (our unpublished results).
Bacterial cells were usually grown on M9 minimal medium with succinate
(20 mM) and/or proline (20 mM) as the sole C source
(
1).
When proline (20 mM) was used as the sole C and N source,
M9 depleted
of ammonium, called M8, was used. When necessary,
kanamycin and
rifampin were added to final concentrations of 25
and 10 µg/ml,
respectively.
Nucleic acid techniques.
The 5' mRNA start of the transcript
that originated from the put promoter was determined by the
method of Marqués et al. (22). The primer used to
analyze expression from putA was
5'-CACCACTTCCTGCTCGGGGCGG-3', and the primer used to
determine putP expression was
5'-GGCGATCCAGGCCTCGGACAGGCCCG-3'. These oligonucleotides
were 5' end labeled with [
-32P]ATP and polynucleotide
kinase, and about 105 cpm of the labeled primers was
annealed to 20 to 30 µg of total RNA prepared from the different
P. putida strains grown under different conditions. cDNA was
synthesized by using avian myeloblastosis virus reverse transcriptase
as previously described (22). The products of reverse
transcription were analyzed in urea-polyacrylamide sequencing gels.
Gels were exposed, during the time required, to Amersham RPN-8 films
for autoradiography.
Nucleotide sequence accession number. The DNA sequence of
the intergenic region between the
putA and
putP
genes can be retrieved
from GenBank under accession number
AF153207.
| |
RESULTS AND DISCUSSION |
We have found that as in members of the family
Enterobacteriaceae, in P. putida the
put genes are transcribed divergently, and we have located
the intergenic region at about 400 bp (Fig. 1). Therefore, this region should contain
all the elements necessary to control expression from the
putA and putP genes. To study the transcription
of the put genes, we have grown P. putida cells on M9 minimal medium with proline as the sole C source (ammonium as the
N source) or N source (succinic acid as the C source) or with proline
as the sole C and N source (1). As a control, we have grown
P. putida cells on M9 minimal medium with ammonium as the N
source and succinate as the sole C source. mRNA from cells growing
exponentially with these nutrients was isolated, and both the presence
and amount of the put mRNAs were analyzed by primer
extension. The results obtained are shown in Fig.
2. It was found that expression of the
put genes was induced because no mRNAs were detected in
cells grown on M9 minimal medium with succinate, whereas in the
presence of proline, regardless of its utilization as C, N, or C and N
source, both genes were expressed. In addition, the absolute expression
levels were similar in the proline concentration range of 200 µM to
20 mM.
View larger version (38K):
[in this window]
[in a new window]
|
FIG. 1.
DNA sequence of the intergenic region between the
putA and putP genes. The ATG start codon of the
genes is boxed; the transcription initiation point of each gene is
marked by an asterisk, and the  10 and 35 regions of each promoter
are underlined.
|
|
View larger version (37K):
[in this window]
[in a new window]
|
FIG. 2.
Expression of the putA and putP
genes of P. putida KT2440 under different growth conditions.
mRNA was prepared as described previously (20). Cells were
grown in different media as follows. Lane 1, M8 minimal medium with 20 mM proline; lane 2, M9 minimal medium with 20 mM proline; lane 3, M9
with 20 mM proline and succinate; lane 4, M9 with succinate. Primer
extension analysis was done as described in Materials and Methods with
a primer complementary to putA or putP mRNA.
|
|
In six independent assays, the level of cDNA resulting from extension
with the putA primer was found to be 3.2- to 5.7-fold higher
than the levels obtained for the putP promoter, which
suggests that the putA promoter is stronger than the
putP promoter. This induction ratio was independent of the
concentration of proline used for induction within the range between
200 µM and 20 mM. In addition, it should be mentioned that glutamate,
the first stable metabolite of proline metabolism, is neither an
inducer of the put genes nor a repressor in cultures growing
with proline and glutamate (not shown). This contrasts with the complex
control of proline utilization in higher microorganisms such as
Aspergillus nidulans (9).
The primer extension analysis shown in Fig. 2 allowed us to determine
the main transcription start site corresponding to nucleotide 140 for
putA and to nucleotide 400 for the putP genes
(Fig. 1). Analysis of the DNA sequence of the region upstream from the
start of each transcript was carried out. In both cases, sequences that resembled those recognized by RNA polymerase with 70
were found (Fig. 1).
P. putida PutA protein is involved in putA
and putP gene expression, and its regulatory role is
independent of its catalytic activity.
In Escherichia
coli and Salmonella enterica serovar Typhimurium, it
has been suggested that not only does the putA gene product have two enzymatic activities but that it also regulates expression of
the put promoters (27). Its role has been
suggested to be that of a repressor protein that binds to the
put region, hindering the access of the RNA polymerase
(27). We previously generated a P. putida putA
null mutant carrying the insertion of a mini-Tn5 at the 5'
end of the putA gene (32). We tested the
expression from the putA and putP promoters in
this isogenic PutA-deficient background. We found that transcription
from the putA and putP promoters was constitutive
(Fig. 3). Since the mini-Tn5
insertion can exert polar effects on downstream genes, we cannot
exclude the possibility that the constitutivity of put genes
in this background is the result of the lack of a yet unidentified
regulator located downstream of putA. To this end, we
analyzed in detail the 3' region of putA. A hairpin
(5'-AAGGAGAGCCTCGGCTCTCCTT-3') that could destabilize RNA
polymerase was found 22 bp downstream from the stop codon. In addition,
no open reading frames were found within the contiguous 600 bp. This
strongly suggests that PutA is involved as a repressor of expression of
the put promoters in P. putida.
View larger version (63K):
[in this window]
[in a new window]
|
FIG. 3.
Expression from the putA and putP
promoters in P. putida KT2442, the PutA-deficient derivative
S14D2, and the PutA Glu896Lys mutant. Cells were grown in the
absence () or presence (+) of proline. The strains were P. putida KT2442 (lanes 1 and 2), P. putida S14D2 (lanes 3 and 4), and P. putida KT2442-Pro21 (lanes 5 and 6). Other
conditions are as described in the legend for Fig. 2.
|
|
P. putida KT2442-Pro21 is a mutant unable to use proline as
the sole C or N source. We have identified that in this mutant
the PutA
protein lacks the ability to mediate proline-to-glutamate
conversion
due to a single point mutation that resulted in the
single amino acid
change Glu896
Lys (S. Vílchez, unpublished
results). We have
analyzed the pattern of expression from the
put promoters in
cells growing with succinate and ammonium in
the absence and presence
of proline. The results obtained are
shown in Fig.
3, where it can be
observed that expression from
the
put promoters followed the
same pattern as in the wild-type
strain. This indicates that the
regulatory role of PutA is independent
of its catabolic activities and
makes PutA a peculiar protein
in the sense that this 1,315-amino-acid
protein has two catabolic
activities and a gene regulatory
function.
Involvement of different sigma factors in the control of expression
of the put genes.
Since the analysis of the upstream
sequences of the put promoters revealed 10 and 35
regions similar to those recognized by 70 and because
some promoters can be transcribed in vivo by 70 or
38 according to the growth phase (13, 30), we
tested expression from the put promoters in cells in the
early stationary phase for both the wild type and the isogenic
38 mutant (25). Proline (2 mM) was added to
cells in the stationary phase, mRNA was isolated 30 min later, and the
level of expression from the putA and putP
promoters was analyzed. It was found that expression from these
promoters was similar in both backgrounds (Fig.
4).
View larger version (43K):
[in this window]
[in a new window]
|
FIG. 4.
Expression from the putA and putP
gene promoters in different host backgrounds. P. putida
cells were grown in the presence (+) or absence () of proline. The
strains used were the wild type (lane 1), IHF-deficient mutant (lane
2), 54-deficient mutant (lane 3),
38-deficient mutant (lane 4), and
ptsN-deficient mutant (lane 5). Other conditions are as
described in the legend for Fig. 2.
|
|
In enterobacteria, several proteins have been proposed to be involved
in transcription from the
put promoters: Nac,
54, and IHF (
18,
27). We had previously
generated
P. putida knockout mutations in the
rpoN gene encoding
54 (
14) and in
the
ihfA gene (
20). To date, the
nac
gene has
not been identified in pseudomonads. In the IHF- and
RpoN-deficient
isogenic backgrounds, we assayed the expression from the
put promoters
in cells growing in the presence of 2 mM
proline, and we compared
the results with those obtained for the
wild-type cells growing
under similar conditions. Culture samples were
taken for mRNA
analysis after 120 min of incubation. The results
obtained are
shown in Fig.
4, where it can be observed that in the
IHF-deficient
background, the expression from the
put
promoters was similar
to that from these promoters in the wild-type
background. However,
in the
54-deficient background,
there was no expression in the presence
of
proline.
Cases et al. (
6) recently reported that in
P. putida KT2440, the
pts genes lie downstream of
rpoN. The
pts genes are part
of an operon with
rpoN. Their study has suggested a regulatory
role for these
genes in processes related to the use of different
C sources by
P. putida. Since the
54-deficient
P. putida strain carries a Tn
5 insertion within the
rpoN gene and because the insertion exerted a polar effect
on
downstream genes, we examined expression from the
put
promoters
in
P. putida MAD2 (Table
1) which is
54 proficient and Pts deficient (Fig.
4). We have found
that in
the MAD2 strain, the pattern of expression from the
put promoters
in the presence of proline was similar to that
found in the wild-type
strain. This result leads to the suggestion that
the lack of expression
of the
put promoters in the
P. putida rpoN mutant is due to the
lack of
54 rather
than to other proteins of the
rpoN-pts operon.
The
54 promoter recognition sequence includes short
elements at nucleotides
12 (GC) and
24 (GC) with extensive
conservation
between the two (
5,
33). Such
54
promoter sequences have not been found upstream from the transcription
initiation start points of the
put genes in
Pseudomonas. Therefore,
we ascribed the lack of expression
from the
put promoters to the
lack of a regulator involved
in the control of the
put promoters
whose expression is
54 dependent. In
Klebsiella aerogenes, the
Nac protein is involved
in control of a number of promoters subject to
nitrogen regulation
(
hutUH,
gdh,
putA,
and
ureA) whose transcription is mediated by
RNA polymerase
with
70. No expression from these promoters occurred in
a
54-deficient background. The reason for this is that
the
nac system
is under the control of the
ntr
system and the
nac gene expression
is dependent on
54 (
3,
18,
24). Therefore, Nac represents a
form of nitrogen
regulation that is not independent of the Ntr system
in enterobacteria.
To date, neither the
nac nor the
ntr system has been reported
in
P. putida. As a
hypothesis, we propose a model for proline
utilization in
Pseudomonas in which an analog of NtrC activates
54-dependent expression of an analog of Nac. The Nac
protein, thus
produced, displaces PutA from the
put promoter
and allows
70-dependent expression of
put
genes. We propose that the main role
of this Nac-like activator in
Pseudomonas is to overcome PutA
repression, since in a
PutA-deficient background, expression from
put is proline
independent.
| |
ACKNOWLEDGMENTS |
This work was supported in part by grants from GX-Biosystems
España and the European Commission (BIO4-CT98-0283).
We thank I. Cases and S. Marqués for kindly providing strains.
| |
FOOTNOTES |
*
Corresponding author. Mailing address:
CSIC-Estación Experimental del Zaidín, Apdo. de Correos
419, E-18008 Granada, Spain. Phone: 34-958-121011. Fax:
34-958-129600.
| |
REFERENCES |
| 1.
|
Abril, M. A.,
C. Michán,
K. N. Timmis, and J. L. Ramos.
1989.
Regulator and enzyme specificities of the TOL plasmid-encoded upper pathway for degradation of aromatic hydrocarbons and expansion of the substrate range of the pathway.
J. Bacteriol.
171:6782-6790[Abstract/Free Full Text].
|
| 2.
|
Allen, S. W.,
A. Sentis Willis, and S. R. Maloy.
1993.
DNA sequence of the putA gene from Salmonella typhimurium: a bifunctional membrane-associated dehydrogenase that binds DNA.
Nucleic Acids Res.
21:1676-1686[Free Full Text].
|
| 3.
|
Bender, R. A.,
P. M. Snyder,
R. Bueno,
M. Quinto, and B. Magasanik.
1983.
Nitrogen regulation system of Klebsiella aerogenes: the nac gene.
J. Bacteriol.
156:444-446[Abstract/Free Full Text].
|
| 4.
|
Brown, E. D., and J. M. Wood.
1993.
Conformational change and membrane association of the PutA protein are coincident with reduction of its FAD cofactor by proline.
J. Biol. Chem.
268:8972-8979[Abstract/Free Full Text].
|
| 5.
|
Buck, M.,
M.-T. Gallegos,
D. J. Studholme,
Y. Guo, and J. D. Gralla.
2000.
The bacterial enhancer-dependent 54 (N) transcription factor.
J. Bacteriol.
182:4129-4136[Free Full Text].
|
| 6.
|
Cases, I.,
J. Pérez-Martín, and V. de Lorenzo.
1999.
The IIANtr (PtsN) protein of Pseudomonas putida mediated C-source inhibition of the 54-dependent Pu promoter of the TOL plasmid.
J. Biol. Chem.
274:15562-15568[Abstract/Free Full Text].
|
| 7.
|
Chen, C. S., and A. Yoshida.
1991.
Enzymatic properties of the proline encoded by newly cloned human alcohol dehydrogenase ADH6 gene.
Biochem. Biophys. Res. Commun.
181:743-747[CrossRef][Medline].
|
| 8.
|
Cho, K.,
C. Fuqua, and S. C. Winans.
1997.
Transcriptional regulation and locations of Agrobacterium tumefaciens genes required for complete catabolism of octopine.
J. Bacteriol.
179:1-8[Abstract/Free Full Text].
|
| 9.
|
Cubero, B.,
D. Gómez, and C. Scazzocchio.
2000.
Metabolite repression and inducer exclusion in the proline utilization gene cluster of Aspergillus.
J. Bacteriol.
182:233-235[Abstract/Free Full Text].
|
| 10.
|
Franklin, F. G. H.,
M. Bagdasarian,
M. M. Bagdasarian, and K. N. Timmis.
1981.
Molecular and functional analysis of the TOL plasmid pWW0 from Pseudomonas putida and cloning genes for the entire regulated aromatic ring meta cleavage pathway.
Proc. Natl. Acad. Sci. USA
78:7458-7462[Abstract/Free Full Text].
|
| 11.
|
Jiménez-Zurdo, J. I.,
P. van Dillewijn,
M. J. Soto,
M. R. de Felipe,
J. Olivares, and N. Toro.
1995.
Characterization of a Rhizobium meliloti proline dehydrogenase mutant altered in nodulation efficiency and competitiveness on alfalfa roots.
Mol. Plant-Microbe Interact.
8:492-498[Medline].
|
| 12.
|
Jiménez-Zurdo, J. I.,
F. M. García-Rodríguez, and N. Toro.
1997.
The Rhizobium meliloti putA gene: its role in the establishment of the symbiotic interaction with alfalfa.
Mol. Microbiol.
23:85-93[CrossRef][Medline].
|
| 13.
|
Jishage, M.,
A. Iwata,
S. Veda, and A. Ishihama.
1996.
Regulation of RNA polymerase sigma subunit synthesis in Escherichia coli: intracellular levels of four species of sigma subunit under various growth conditions.
J. Bacteriol.
178:5447-5451[Abstract/Free Full Text].
|
| 14.
|
Keuntje, B.,
B. Masepohl, and W. Klipp.
1995.
Expression of the putA gene encoding proline dehydrogenase from Rhodobacter capsulatus is independent of NtrC regulation but requires an Lrp-like activator protein.
J. Bacteriol.
177:6432-6439[Abstract/Free Full Text].
|
| 15.
|
Kohl, D. H.,
K. R. Schubert,
M. B. Carter,
C. H. Hagedam, and G. Shearer.
1988.
Proline metabolism in N2-fixing root nodules: energy transfer and regulation of purine synthesis.
Proc. Natl. Acad. Sci. USA
85:2036-2040[Abstract/Free Full Text].
|
| 16.
|
Köhler, T.,
S. Harayama,
J.-L. Ramos, and K. N. Timmis.
1989.
Involvement of Pseudomonas putida RpoN factor in regulation of various metabolic functions.
J. Bacteriol.
171:4326-4333[Abstract/Free Full Text].
|
| 17.
|
Ling, M.,
S. W. Allen, and J. M. Wood.
1994.
Sequence analysis identifies the proline dehydrogenase and  1-pyrroline-5-carboxylate dehydrogenase domains of the multifunctional Escherichia coli PutA protein.
J. Mol. Biol.
243:950-956[CrossRef][Medline].
|
| 18.
|
Macaluso, A.,
E. A. Best, and R. A. Bender.
1990.
Role of the nac gene product in the nitrogen regulation of some NTR-regulated operons of Klebsiella aerogenes.
J. Bacteriol.
172:7249-7255[Abstract/Free Full Text].
|
| 19.
|
Maloy, S. R.
1987.
The proline utilization operon, p. 1513-1519.
In
F. C. Neidhardt, J. L. Ingraham, K. B. Low, B. Magasanik, M. Schaechter, and H. E. Umbarger (ed.), Escherichia coli and Salmonella typhimurium: cellular and molecular biology. American Society for Microbiology, Washington, D.C.
|
| 20.
|
Marqués, S.,
M.-T. Gallegos,
M. Manzanera,
A. Holtel,
K. N. Timmis, and J. L. Ramos.
1998.
Activation and repression of transcription at the double tandem divergent promoters for the xylR and xylS genes of the TOL plasmid of Pseudomonas putida.
J. Bacteriol.
180:2889-2894[Abstract/Free Full Text].
|
| 21.
|
Marqués, S.,
M. T. Gallegos, and J. L. Ramos.
1995.
Role of S in transcription from the positively controlled Pm promoter of the TOL plasmid of Pseudomonas putida.
Mol. Microbiol.
18:851-857[CrossRef][Medline].
|
| 22.
|
Marqués, S.,
J. L. Ramos, and K. N. Timmis.
1993.
Analysis of the mRNA structure of the Pseudomonas putida TOL meta fission pathway operon around the transcription initiation point, the xylTE and the xylFJ regions.
Biochim. Biophys. Acta
1216:227-236[Medline].
|
| 23.
|
Molina, L.,
C. Ramos,
E. Duque,
M. C. Ronchel,
J. M. García,
L. Wyke, and J. L. Ramos.
2000.
Survival of Pseudomonas putida KT2440 in soil and in the rhizosphere of plants under greenhouse and environmental conditions.
Soil. Biol. Biochem.
32:315-321[CrossRef].
|
| 24.
|
Muro-Pastor, A. M.,
P. Ostrowsky, and S. Maloy.
1997.
Regulation of gene expression by repressor localization: biochemical evidence that membrane and DNA binding by the PutA protein are mutually exclusive.
J. Bacteriol.
179:2788-2791[Abstract/Free Full Text].
|
| 25.
|
Nieuwkoop, A. J.,
S. A. Baldauf,
M. E. S. Hudspeth, and R. A. Bender.
1988.
Bidirectional promoter in the hut(P) region of the histidine utilization (hut) operons from Klebsiella aerogenes.
J. Bacteriol.
170:2240-2246[Abstract/Free Full Text].
|
| 26.
|
O'Brien, K.,
G. Deno,
P. Ostrovsky de Spicer,
J. F. Gadner, and S. Maloy.
1992.
Integration host factor facilitates repression of the put operon in Salmonella typhimurium.
Gene
118:13-19[CrossRef][Medline].
|
| 27.
|
Ostrovsky de Spicer, P.,
K. O'Brien, and S. Maloy.
1991.
Regulation of proline utilization in Salmonella typhimurium: a membrane-associated dehydrogenase binds DNA in vitro.
J. Bacteriol.
173:211-219[Abstract/Free Full Text].
|
| 28.
|
Ramos-González, M. I., and S. Molin.
1998.
Cloning, sequencing, and phenotypic characterization of the rpoS gene from Pseudomonas putida KT2440.
J. Bacteriol.
180:3421-3431[Abstract/Free Full Text].
|
| 29.
|
Soto, M. J.,
J. I. Jiménez-Zurdo,
P. van Dillewijn, and N. Toro.
2000.
Sinorhizobium meliloti putA gene regulation: a new model within the family Rhizobiaceae.
J. Bacteriol.
182:1935-1941[Abstract/Free Full Text].
|
| 30.
|
Tanaka, K.,
Y. Tanayanagi,
N. Fujita,
A. Ishihama, and H. Takahashi.
1993.
Heterogeneity of the principal factor in Escherichia coli: the rpoS gene product, 38, is second principal factor of RNA polymerase in stationary-phase.
Proc. Natl. Acad. Sci. USA
90:3511-3515[Abstract/Free Full Text].
|
| 31.
|
Vancura, V.
1988.
Plant metabolites in soil, p. 156-168.
In
F. Kunc, and V. Vancura (ed.), Soil microbial associations: control of structures and functions. Elsevier, Amsterdam, The Netherlands.
|
| 32.
|
Vílchez, S.,
L. Molina,
C. Ramos, and J. L. Ramos.
2000.
Proline catabolism by Pseudomonas putida: cloning, characterization, and expression of the put genes.
J. Bacteriol.
182:91-99[Abstract/Free Full Text].
|
| 33.
|
Wang, L., and J. D. Gralla.
1998.
Multiple in vivo roles for the 12-region elements of 54 promoters.
J. Bacteriol.
180:5626-5631[Abstract/Free Full Text].
|
| 34.
|
Worsey, M. J., and P. A. Williams.
1975.
Metabolism of toluene and xylenes by Pseudomonas putida (arvilla) mt-2: evidence for a new function of the TOL plasmid.
J. Bacteriol.
124:7-13[Abstract/Free Full Text].
|
| 35.
|
Zhu, Y.-X.,
G. Shearer, and D. H. Kohl.
1992.
Proline fed to intact soybean plants influences acetylene reducing activity, and content and metabolism of proline in bacteroids.
Plant Physiol.
98:1020-1028[Abstract/Free Full Text].
|
Applied and Environmental Microbiology, December 2000, p. 5221-5225, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
Fernandez-Pinar, R., Ramos, J. L., Rodriguez-Herva, J. J., Espinosa-Urgel, M.
(2008). A Two-Component Regulatory System Integrates Redox State and Population Density Sensing in Pseudomonas putida. J. Bacteriol.
190: 7666-7674
[Abstract]
[Full Text]
-
Krishnan, N., Becker, D. F.
(2006). Oxygen Reactivity of PutA from Helicobacter Species and Proline-Linked Oxidative Stress. J. Bacteriol.
188: 1227-1235
[Abstract]
[Full Text]
-
Gu, D., Zhou, Y., Kallhoff, V., Baban, B., Tanner, J. J., Becker, D. F.
(2004). Identification and Characterization of the DNA-binding Domain of the Multifunctional PutA Flavoenzyme. J. Biol. Chem.
279: 31171-31176
[Abstract]
[Full Text]
-
Revelles, O., Espinosa-Urgel, M., Molin, S., Ramos, J. L.
(2004). The davDT Operon of Pseudomonas putida, Involved in Lysine Catabolism, Is Induced in Response to the Pathway Intermediate {delta}-Aminovaleric Acid. J. Bacteriol.
186: 3439-3446
[Abstract]
[Full Text]
-
Sonawane, A., Kloppner, U., Hovel, S., Volker, U., Rohm, K.-H.
(2003). Identification of Pseudomonas proteins coordinately induced by acidic amino acids and their amides: a two-dimensional electrophoresis study. Microbiology
149: 2909-2918
[Abstract]
[Full Text]
Top
Abstract
Introduction
