Steen Anton, Buist Girbe, Kramer Naomi E, Jalving Ruud, Benus Germaine F J D, Venema Gerard, Kuipers Oscar P, Kok Jan
Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
Appl Environ Microbiol. 2008 Aug;74(15):4671-9. doi: 10.1128/AEM.00103-08. Epub 2008 Jun 6.
When Lactococcus lactis subsp. lactis IL1403 or L. lactis subsp. cremoris MG1363 is grown in a medium with galactose as the carbon source, the culture lyses to a lesser extent in stationary phase than when the bacteria are grown in a medium containing glucose. Expression of AcmA, the major autolysin of L. lactis, is not influenced by the carbon source. Binding studies with a fusion protein consisting of the MSA2 protein of Plasmodium falciparum and the C-terminal peptidoglycan-binding domain of AcmA revealed that cell walls of cells from both subspecies grown on galactose bind less AcmA than cell walls of cells grown on glucose. Cells grown on glucose or galactose and treated with trichloroacetic acid prior to AcmA binding bind similar amounts of AcmA. Analysis of the composition of the lipoteichoic acids (LTAs) of L. lactis IL1403 cells grown on glucose or galactose showed that the LTA composition is influenced by the carbon source: cells grown on galactose contain LTA with less galactose than cells grown on glucose. In conclusion, growth of L. lactis on galactose changes the LTA composition in the cell wall in such a way that less AcmA is able to bind to the peptidoglycan, resulting in a decrease in autolysis.
当乳酸乳球菌乳亚种IL1403或乳酸乳球菌乳脂亚种MG1363在以半乳糖作为碳源的培养基中生长时，与在含有葡萄糖的培养基中生长相比，培养物在稳定期的裂解程度较小。乳酸乳球菌主要自溶素AcmA的表达不受碳源的影响。对由恶性疟原虫的MSA2蛋白和AcmA的C端肽聚糖结合结构域组成的融合蛋白进行的结合研究表明，在半乳糖上生长的两个亚种细胞的细胞壁比在葡萄糖上生长的细胞的细胞壁结合的AcmA更少。在结合AcmA之前用三氯乙酸处理过的在葡萄糖或半乳糖上生长的细胞结合的AcmA量相似。对在葡萄糖或半乳糖上生长的乳酸乳球菌IL1403细胞的脂磷壁酸（LTA）组成进行分析表明，LTA组成受碳源影响：在半乳糖上生长的细胞所含LTA中的半乳糖比在葡萄糖上生长的细胞少。总之，乳酸乳球菌在半乳糖上生长会改变细胞壁中的LTA组成，使得能够与肽聚糖结合的AcmA减少，从而导致自溶作用减弱。
