PMID:15943817

Citation	Steen, A, Buist, G, Horsburgh, GJ, Venema, G, Kuipers, OP, Foster, SJ and Kok, J (2005) AcmA of Lactococcus lactis is an N-acetylglucosaminidase with an optimal number of LysM domains for proper functioning. FEBS J. 272:2854-68
Abstract	AcmA, the major autolysin of Lactococcus lactis MG1363 is a modular protein consisting of an N-terminal active site domain and a C-terminal peptidoglycan-binding domain. The active site domain is homologous to that of muramidase-2 of Enterococcus hirae, however, RP-HPLC analysis of muropeptides released from Bacillus subtilis peptidoglycan, after digestion with AcmA, shows that AcmA is an N-acetylglucosaminidase. In the C-terminus of AcmA three highly similar repeated regions of 45 amino acid residues are present, which are separated by short nonhomologous sequences. The repeats of AcmA, which belong to the lysine motif (LysM) domain family, were consecutively deleted, removed, or, alternatively, one additional repeat was added, without destroying the cell wall-hydrolyzing activity of the enzyme in vitro, although AcmA activity was reduced in all cases. In vivo, proteins containing no or only one repeat did not give rise to autolysis of lactococcal cells, whereas separation of the producer cells from the chains was incomplete. Exogenously added AcmA deletion derivatives carrying two repeats or four repeats bound to lactococcal cells, whereas the derivative with no or one repeat did not. In conclusion, these results show that AcmA needs three LysM domains for optimal peptidoglycan binding and biological functioning.
Links	PubMed Online version:10.1111/j.1742-4658.2005.04706.x
Keywords	Acetylglucosaminidase/chemistry; Acetylglucosaminidase/metabolism; Bacillus subtilis/enzymology; Binding Sites; Cell Wall/chemistry; Cell Wall/metabolism; Lactococcus lactis/chemistry; Lactococcus lactis/enzymology; Muramidase/chemistry; Muramidase/metabolism; Peptidoglycan/chemistry; Peptidoglycan/metabolism; Protein Structure, Tertiary
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LACLM:ACMA		GO:0061784: peptidoglycan N-acetylglucosaminidase activity	ECO:0000314:		F		Figure 5 A-C Identifies the hydrolytic specificity of AcmA by RP-HPLC of muropeptides.	complete CACAO 12200

References

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