PMID:22228730

Citation	Ju, CX, Gu, HW and Lu, CP (2012) Characterization and functional analysis of atl, a novel gene encoding autolysin in Streptococcus suis. J. Bacteriol. 194:1464-73
Abstract	Streptococcus suis serotype 2 (S. suis 2) is an important swine and human pathogen responsible for septicemia and meningitis. A novel gene, designated atl and encoding a major autolysin of S. suis 2 virulent strain HA9801, was identified and characterized in this study. The Atl protein contains 1,025 amino acids with a predicted molecular mass of 113 kDa and has a conserved N-acetylmuramoyl-l-alanine amidase domain. Recombinant Atl was expressed in Escherichia coli, and its bacteriolytic and fibronectin-binding activities were confirmed by zymography and Western affinity blotting. Two bacteriolytic bands were shown in the sodium dodecyl sulfate extracts of HA9801, while both were absent from the atl inactivated mutant. Cell chains of the mutant strain became longer than that of the parental strain. In the autolysis assay, HA9801 decreased to 20% of the initial optical density (OD) value, while the mutant strain had almost no autolytic activity. The biofilm capacity of the atl mutant was reduced ∼30% compared to the parental strain. In the zebrafish infection model, the 50% lethal dose of the mutant strain was increased up to 5-fold. Furthermore, the adherence to HEp-2 cells of the atl mutant was 50% less than that of the parental strain. Based on the functional analysis of the recombinant Atl and observed effects of atl inactivation on HA9801, we conclude that Atl is a major autolysin of HA9801. It takes part in cell autolysis, separation of daughter cells, biofilm formation, fibronectin-binding activity, cell adhesion, and pathogenesis of HA9801.
Links	PubMed PMC3294825 Online version:10.1128/JB.06231-11
Keywords	Animals; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biofilms/growth & development; Cell Adhesion; Disease Models, Animal; Electrophoresis, Polyacrylamide Gel; Escherichia coli/genetics; Fibronectins/metabolism; Gene Deletion; Gene Expression; Hep G2 Cells; Humans; Lethal Dose 50; Molecular Weight; N-Acetylmuramoyl-L-alanine Amidase/chemistry; N-Acetylmuramoyl-L-alanine Amidase/genetics; N-Acetylmuramoyl-L-alanine Amidase/metabolism; Protein Binding; Protein Structure, Tertiary; Recombinant Proteins/genetics; Recombinant Proteins/metabolism; Streptococcal Infections/microbiology; Streptococcus suis/enzymology; Streptococcus suis/genetics; Streptococcus suis/growth & development; Streptococcus suis/metabolism; Survival Analysis; Virulence; Zebrafish
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRSU:A5JSI3		GO:0008745: N-acetylmuramoyl-L-alanine amidase activity	ECO:0000315:		F		IMP was demonstrated based on Figure 2, which shows autolysin profile of wild type and complementation strain. The lytic pattern was absent in the mutant strain.	complete CACAO 4164

References

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