Characterization of AcmB, an N-acetylglucosaminidase autolysin from Lactococcus lactis.
A gene encoding a putative peptidoglycan hydrolase, named acmB, which is a paralogue of the major autolysin acmA gene, was identified in the Lactococcus lactis genome sequence. The acmB gene is transcribed in L. lactis MG1363 and its expression is modulated during cellular growth. The encoded AcmB protein has a modular structure with three domains: an N-terminal domain, especially rich in Ser, Thr, Pro and Asn residues, resembling a cell-wall-associated domain; a central domain homologous to the Enterococcus hirae muramidase catalytic domain; and a C-terminal domain of unknown function. A recombinant AcmB derivative, devoid of its N-terminal domain, was expressed in Escherichia coli. It exhibited hydrolysing activity on the peptidoglycan of several Gram-positive bacteria, including L. lactis. Though showing sequence similarity with enterococcal muramidase, AcmB has N-acetylglucosaminidase specificity. The acmB gene was inactivated in order to evaluate the role of the enzyme. AcmB does not appear to be involved in cell separation but contributes to cellular autolysis.
Huard
Carine
C
Unité de Biochimie et Structure des Protéines, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
Miranda
Guy
G
Unité de Biochimie et Structure des Protéines, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
Wessner
Françoise
F
Unité de Biochimie et Structure des Protéines, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
Bolotin
Alexander
A
Unité de Biochimie et Unité de Génétique Microbienne, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
Hansen
Jonathan
J
Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
Foster
Simon J
SJ
Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
Chapot-Chartier
Marie-Pierre
MP
Unité de Biochimie et Structure des Protéines, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France.
D000118:Acetylglucosaminidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001433:Bacteriolysis; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism*; D010457:Peptidoglycan / Q000378:metabolism; D017422:Sequence Analysis, DNA
D010457:Peptidoglycan; D000118:Acetylglucosaminidase; D009238:N-Acetylmuramoyl-L-alanine Amidase