Influence of proteins Bsp and FemH on cell shape and peptidoglycan composition in group B streptococcus

Department of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany 1 Department of Microbiology, GBF-National Research Centre for Biotechnology,D-38124 Braunschweig, Germany 2 Bayer AG, PH Research Antiinfectives I, D-42096 Wuppertal, Germany 3 Institute for Organic Chemistry, University of Tübingen, D-72070 Tübingen, Germany 4 Author for correspondence: Dieter Reinscheid. Tel: +49 731 5024853. Fax: +49 731 5022719. e-mail: dieter.reinscheid{at}biologie.uni-ulm.de Group B streptococcus (GBS) is surrounded by a capsule. However, little is known about peptidoglycan metabolism in these bacteria. In the present study, a 65 kDa protein was isolated from the culture supernatant of GBS and N-terminally sequenced, permitting isolation of the corresponding gene, termed bsp . The bsp gene was located close to another gene, designated femH , and reverse transcription-PCR revealed a bicistronic transcriptional organization for both genes. The Bsp protein was detected in the culture supernatant from 31 tested clinical isolates of GBS, suggesting a wide distribution of Bsp in these bacteria. Overexpression of bsp resulted in lens-shaped GBS cells, indicating a role for bsp in controlling cell morphology. Insertional disruption of femH resulted in a reduction of the L-alanine content of the peptidoglycan, suggesting that femH is involved in the incorporation of L-alanine residues in the interpeptide chain of the peptidoglycan of GBS. Keywords: Streptococcus agalactiae , murein hydrolase, fem -like genes Abbreviations: GBS, group B streptococcus c The GenBank accession number for the sequence reported in this paper is AJ305309 . a Present address: Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong SAR, China.