Service de Bactériologie-Virologie, INSERM U914 'Emerging Resistance to Antibiotics', Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine et Université Paris Sud, 94275 Le K.-Bicêtre, France.
J Antimicrob Chemother. 2012 Nov;67(11):2661-4. doi: 10.1093/jac/dks289. Epub 2012 Jul 31.
In silico analysis identified a metallo-β-lactamase (MBL) in Erythrobacter litoralis HTCC2594, sharing 55% amino acid identity with NDM-1. The aim of this work was to characterize the chromosomally encoded MBLs from several Erythrobacter spp. that may represent potential reservoirs of acquired MBLs.
Erythrobacter citreus, Erythrobacter flavus, Erythrobacter longus, Erythrobacter aquimaris and Erythrobacter vulgaris were from the Pasteur Institute collection, France. DNA was extracted and used for shotgun cloning, and β-lactamases were expressed in Escherichia coli. MICs for resulting E. coli recombinant strains were determined by Etest. The deduced amino acid sequences were analysed and compared with BLASTP. Enzymatic activity of bacterial extracts from recombinant E. coli strains was determined by UV spectrophotometry with imipenem (100 μM) as substrate.
Resulting E. coli recombinant strains harboured hypothetical MBL-encoding genes. MICs of β-lactams showed decreased susceptibility to carbapenems only for E. coli (pFLA-1) and E. coli (pLON-1), expressing the MBL from E. flavus and E. longus, respectively. MBLs from different Erythrobacter spp. shared weak amino acid identity, ranging from 45% to75% identity. They differed greatly from that of E. litoralis HTCC2594 (and NDM-1), sharing only 11%-23% identity. Enzymatic activity against imipenem was detectable but weak in all these recombinant E. coli strains, except E. coli (pFLA-1), in which specific activity was significantly higher.
Several chromosomally located MBLs have been identified from Erythrobacter spp. They share weak amino acid identity and are very weakly related to other acquired MBLs (10%-23%).
通过计算机分析，在海栖热袍菌 HTCC2594 中发现一种金属β-内酰胺酶（MBL），与 NDM-1 的氨基酸序列相似度为 55%。本研究旨在对几种海栖热袍菌属中可能代表获得性 MBL 潜在储库的染色体编码 MBL 进行特征描述。
从法国巴斯德研究所收集的黄色海栖热袍菌、黄色海栖热袍菌、长海栖热袍菌、Aquimaris 海栖热袍菌和普通海栖热袍菌中提取 DNA 进行鸟枪法克隆，并在大肠杆菌中表达β-内酰胺酶。通过 Etest 测定产生的大肠杆菌重组菌株的 MIC。分析推导的氨基酸序列并与 BLASTP 进行比较。通过用亚胺培南（100 μM）作为底物的紫外分光光度法测定来自重组大肠杆菌菌株的细菌提取物的酶活性。
产生的大肠杆菌重组菌株携带假设的 MBL 编码基因。只有表达来自黄色海栖热袍菌和长海栖热袍菌的 MBL 的大肠杆菌（pFLA-1）和大肠杆菌（pLON-1）对碳青霉烯类的β-内酰胺类药物的 MIC 显示出降低的敏感性。来自不同海栖热袍菌的 MBL 共享较弱的氨基酸同一性，范围为 45%至 75%。它们与海栖热袍菌 HTCC2594（和 NDM-1）的差异非常大，仅共享 11%-23%的同一性。除了大肠杆菌（pFLA-1），所有这些重组大肠杆菌菌株中均检测到针对亚胺培南的酶活性，但活性较弱，而在大肠杆菌（pFLA-1）中，特异性活性明显更高。
从海栖热袍菌属中鉴定出几种染色体定位的 MBL。它们共享较弱的氨基酸同一性，与其他获得性 MBL（10%-23%）非常相关。
