RT Journal Article SR Electronic(1) A1 Anzengruber, Julia A1 Courtin, Pascal A1 Claes, Ingmar J. J. A1 Debreczeny, Monika A1 Hofbauer, Stefan A1 Obinger, Christian A1 Chapot-Chartier, Marie-Pierre A1 Vanderleyden, Jos A1 Messner, Paul A1 Schäffer, ChristinaYR 2014 T1 Biochemical characterization of the major N-acetylmuramidase from Lactobacillus buchneri JF Microbiology, VO 160 IS 8 SP 1807 OP 1819 DO https://doi.org/10.1099/mic.0.078162-0 PB Microbiology Society, SN 1465-2080, AB Bacterial cell wall hydrolases are essential for peptidoglycan remodelling in regard to bacterial cell growth and division. In this study, peptidoglycan hydrolases (PGHs) of different Lactobacillus buchneri strains were investigated. First, the genome sequence of L. buchneri CD034 and L. buchneri NRRL B-30929 was analysed in silico for the presence of PGHs. Of 23 putative PGHs with different predicted hydrolytic specificities, the glycosyl hydrolase family 25 domain-containing homologues LbGH25B and LbGH25N from L. buchneri CD034 and NRRL B-30929, respectively, were selected and characterized in detail. Zymogram analysis confirmed hydrolysing activity on bacterial cell walls for both enzymes. Subsequent reversed-phase HPLC and MALDI-TOF MS analysis of the peptidoglycan breakdown products from L. buchneri strains CD034 and NRRL B-30929, and from Lactobacillus rhamnosus GG, which served as a reference, revealed that LbGH25B and LbGH25N have N-acetylmuramidase activity. Both enzymes were identified as cell wall-associated proteins by means of immunofluorescence microscopy and cellular fractionation, as well as by the ability of purified recombinant LbGH25B and LbGH25N to bind to L. buchneri cell walls in vitro. Moreover, similar secondary structures mainly composed of β-sheets and nearly identical thermal stabilities with T m values around 49 °C were found for the two N-acetylmuramidases by far-UV circular dichroism spectroscopy. The functional and structural data obtained are discussed and compared to related PGHs. In this study, a major N-acetylmuramidase from L. buchneri was characterized in detail for the first time., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.078162-0