Cloning and characterization of the fmt gene which affects the methicillin resistance level and autolysis in the presence of triton X-100 in methicillin-resistant Staphylococcus aureus
Cloning and characterization of the fmt gene which affects the methicillin resistance level and autolysis in the presence of triton X-100 in methicillin-resistant Staphylococcus aureus
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DOI：
10.1128/aac.41.11.2355
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发表时间：
1997-11-01
影响因子：
4.9
通讯作者：
Suginaka, H
中科院分区：
文献类型：
--
作者：
Komatsuzawa, H;Sugai, M;Suginaka, H
在耐甲氧西林金黄色葡萄球菌（MRSA）菌株中，Triton X-100降低了oxacillin耐药水平，尽管降低程度因菌株而异。为了研究MRSA菌株对Triton X-100的反应，我们分离了COL菌株的Tn551插入突变体，该突变体在0.02% Triton X-100的存在下对oxacillin更敏感。该突变体的Tn551插入被转导回亲本菌株、其他MRSA菌株（菌株KSA8和NCTC 10443）和甲氧西林敏感菌株RN450。在0.02% Triton X-100的存在下，MRSA菌株的所有转导剂对oxacillin的耐药水平均有所降低，而RN450的转导剂则没有。在缺乏0.02% Triton X-100的情况下，KSA8的Tn551突变体和NCTC 10443的耐药水平也有所降低。在0.02% Triton X-100的存在下，转导剂的自溶率显著提高。肽聚糖的氨基酸分析和热灭活细胞对几种溶菌酶的敏感性测试表明，亲本与各自的Tn551突变体之间没有显著差异。Tn551插入位点与之前确定的fem和llm位点不同。克隆和测序结果表明，Tn551插入了一个名为fmt的新基因的c端。推测的Fmt蛋白表现出与金黄色葡萄球菌青霉素结合蛋白相似的亲水模式，并含有青霉素结合蛋白和β -内酰胺酶共有的三个保守基序中的两个，表明Fmt可能参与细胞壁合成。
In methicillin-resistant Staphylococcus aureus (MRSA) strains, Triton X-100 reduced the oxacillin resistance level, although the degree of reduction varied from strain to strain. To study the responses of MRSA strains to Triton X-100, we isolated a Tn551 insertion mutant of the COL strain that became more susceptible to oxacillin in the presence of 0.02% Triton X-100. The Tn551 insertion of the mutant was transduced back to the parent strain, other MRSA strains (strains KSA8 and NCTC 10443), and methicillin-susceptible strain RN450. All transductants of MRSA strains had reduced levels of resistance to oxacillin in the presence of 0.02% Triton X-100, while those of RN450 did not. Tn551 mutants of KSA8 and NCTC 10443 also had reduced levels of resistance in the absence of 0.02% Triton X-100. The autolysis rates of the transductants in the presence of 0.02% Triton X-100 were significantly increased. Amino acid analysis of peptidoglycan and testing of heat-inactivated cells for their susceptibilities to several bacteriolytic enzymes showed that there were no significant differences between the parents and the respective Tn551 mutants. The Tn551 insertion site mapped at a location different from the previously identified fem and llm sites. Cloning and sequencing showed that Tn551 had inserted at the C-terminal region of a novel gene designated fmt. The putative Fmt protein showed a hydropathy pattern similar to that of S. aureus penicillin-binding proteins and contained two of the three conserved motifs shared by penicillin-binding proteins and beta-lactamases, suggesting that fmt may be involved in cell wall synthesis.