Xiao Jinhe, Huang Jianguo, Xue Xuemei, Wang Chen, Sun Yanting, Zheng Liangjun, Zhao Xu, Wang Xiaokun, Zhao Xin, Xue Huping
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, People's Republic of China.
Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada.
J Antimicrob Chemother. 2023 Feb 1;78(2):440-444. doi: 10.1093/jac/dkac410.
A defining feature of MRSA is the SCCmec element. The excision and integration of SCCmec elements are catalysed by Ccr recombinases. Currently, seven ccrA, eight ccrB and two ccrC allotypes have been described. However, there have been no recent reports of a novel Ccr recombinase and thus this area should be explored.
According to the proposed criteria of the International Working Group on the Classification of Staphylococcal Cassette Chromosome Elements (IWG-SCC) committee, novel ccr genes were explored by searching the genome of our laboratory staphylococcal strains, which were isolated from bovine mastitis in Northwest China. The biological activity of the novel Ccr recombinases to excise and integrate SCCmec elements was determined. The distribution of the novel ccr genes in staphylococci was conducted by querying the NCBI nr/nt database.
We report a set of novel Ccr recombinases CcrA8B9, which share nucleotide identities of 46.6%-50.2% and 47.4%-52.8% with the ccrA and ccrB alleles, respectively. We used PCR to show that CcrA8B9 can excise and integrate the SCCmec element. Furthermore, using NCBI BLAST we showed that the ccrA8B9 genes exist in other staphylococcal strains. Unlike the common ccr genes, ccrA8B9 is located outside the SCCmec/SCC element.
The novel Ccr recombinases CcrA8B9 can help excise and integrate SCCmec/SCC from the genome and provide a new way to facilitate the transmission of SCCmec/SCC elements among staphylococci.
耐甲氧西林金黄色葡萄球菌（MRSA）的一个决定性特征是葡萄球菌盒式染色体（SCCmec）元件。SCCmec元件的切除和整合由Ccr重组酶催化。目前，已描述了7种ccrA、8种ccrB和2种ccrC同种异型。然而，最近没有关于新型Ccr重组酶的报道，因此该领域应加以探索。
根据葡萄球菌盒式染色体元件分类国际工作组（IWG-SCC）委员会提出的标准，通过搜索我们实验室从中国西北奶牛乳腺炎中分离的葡萄球菌菌株的基因组来探索新型ccr基因。测定新型Ccr重组酶切除和整合SCCmec元件的生物学活性。通过查询NCBI nr/nt数据库来研究新型ccr基因在葡萄球菌中的分布。
我们报道了一组新型Ccr重组酶CcrA8B9，其与ccrA和ccrB等位基因的核苷酸同一性分别为46.6%-50.2%和47.4%-52.8%。我们用PCR证明CcrA8B9能切除和整合SCCmec元件。此外，使用NCBI BLAST我们表明ccrA8B9基因存在于其他葡萄球菌菌株中。与常见的ccr基因不同，ccrA8B9位于SCCmec/SCC元件之外。
新型Ccr重组酶CcrA8B9有助于从基因组中切除和整合SCCmec/SCC，并为促进SCCmec/SCC元件在葡萄球菌间的传播提供了新途径。
