This Article Full Text Full Text (PDF) Other Versions of this Article: AEM.02332-07v1 74/9/2759    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Shimotsuura, I. Articles by Nakashima, S. PubMed PubMed Citation Articles by Shimotsuura, I. Articles by Nakashima, S. Agricola Articles by Shimotsuura, I. Articles by Nakashima, S.

Biochemical and Molecular Characterization of a Novel Type of Mutanase from Paenibacillus sp. Strain RM1: Identification of Its Mutan-Binding Domain, Essential for Degradation of Streptococcus mutans Biofilms

Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan,¹ Oral Care Research Laboratories, Lion Corporation, 3-7 Honjyo 1-chome, Sumida-ku, Tokyo 130-8644, Japan,² Biological Science Research Laboratories, Lion Corporation, 100 Tajima, Odawara, Kanagawa 256-0811, Japan,³ C3-Jian, Los Angeles, California⁴

Received 16 October 2007/ Accepted 26 February 2008

A novel type of mutanase (termed mutanase RM1) was isolated from Paenibacillus sp. strain RM1. The purified enzyme specifically hydrolyzed -1,3-glucan (mutan) and effectively degraded biofilms formed by Streptococcus mutans, a major etiologic agent in the progression of dental caries, even following brief incubation. The nucleotide sequence of the gene for this protein contains a 3,873-bp open reading frame encoding 1,291 amino acids with a calculated molecular mass of 135 kDa. The protein contains two major domains, the N-terminal domain (277 residues) and the C-terminal domain (937 residues), separated by a characteristic sequence composed of proline and threonine repeats. The characterization of the recombinant proteins for each domain which were expressed in Escherichia coli demonstrated that the N-terminal domain had strong mutan-binding activity but no mutanase activity whereas the C-terminal domain was responsible for mutanase activity but had mutan-binding activity significantly lower than that of the intact protein. Importantly, the biofilm-degrading activity observed with the intact protein was not exhibited by either domain alone or in combination with the other. Therefore, these results indicate that the structural integrity of mutanase RM1 containing the N-terminal mutan-binding domain is required for the biofilm-degrading activity.

Published ahead of print on 7 March 2008.