Long-Chain N-Acyl Amino Acid Synthases Are Linked to the Putative PEP-CTERM/Exosortase Protein-Sorting System in Gram-Negative Bacteria
Long-Chain N-Acyl Amino Acid Synthases Are Linked to the Putative PEP-CTERM/Exosortase Protein-Sorting System in Gram-Negative Bacteria
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DOI：
10.1128/jb.05426-11
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发表时间：
2011-10-01
影响因子：
3.2
通讯作者：
Brady, Sean F.
中科院分区：
文献类型：
--
作者：
Craig, Jeffrey W.;Cherry, Marisa A.;Brady, Sean F.
编码长链 N-酰基氨基酸生物合成的克隆经常从土壤宏基因组文库基于活性的筛选中回收。被称为 N-酰基氨基酸合酶的多种酶的成员负责迄今为止表征的所有宏基因组衍生的 N-酰基氨基酸的产生。根据从宏基因组样本中鉴定出 N-酰基氨基酸合酶基因的频率，预计相关基因在整个细菌宏基因组中是常见的。然而，在培养细菌物种的测序基因组中，宏基因组衍生的 N-酰基氨基酸合酶基因的同源物很少。为了了解 N-酰基氨基酸在环境细菌中发挥的作用，我们寻找与宏基因组衍生的 N-酰基氨基酸合酶基因位置相关的保守遗传特征。该分析表明，N-酰基氨基酸合酶基因经常与预测编码含有 PEP-CTERM 基序的蛋白质的基因相邻，并且在某些情况下，与 PEP-CTERM/外切分酶系统的其他保守元件相邻。尽管人们对 PEP-CTERM/外切酶系统知之甚少，但其核心成分被认为代表革兰氏阳性菌的 LPXTG/分切酶蛋白质分选系统的推定革兰氏阴性等价物。在这项调查过程中，我们能够提供证据表明，一个未表征的假设酰基转移酶家族（之前通过生物信息学与 PEP-CTERM/外切酶系统联系起来）是一个新的 N-酰基氨基酸合酶家族，广泛分布在含有 PEP-CTERM/外切酶系统的变形菌中。
Clones that encode the biosynthesis of long-chain N-acyl amino acids are frequently recovered from activity-based screens of soil metagenomic libraries. Members of a diverse set of enzymes referred to as N-acyl amino acid synthases are responsible for the production of all metagenome-derived N-acyl amino acids characterized to date. Based on the frequency at which N-acyl amino acid synthase genes have been identified from metagenomic samples, related genes are expected to be common throughout the global bacterial metagenome. Homologs of metagenome-derived N-acyl amino acid synthase genes are scarce, however, within the sequenced genomes of cultured bacterial species. Toward the goal of understanding the role(s) played by N-acyl amino acids in environmental bacteria, we looked for conserved genetic features that are positionally linked to metagenome-derived N-acyl amino acid synthase genes. This analysis revealed that N-acyl amino acid synthase genes are frequently found adjacent to genes predicted to encode PEP-CTERM motif-containing proteins and, in some cases, other conserved elements of the PEP-CTERM/exosortase system. Although relatively little is known about the PEP-CTERM/exosortase system, its core components are believed to represent the putative Gram-negative equivalent of the LPXTG/sortase protein-sorting system of Gram-positive bacteria. During the course of this investigation, we were able to provide evidence that an uncharacterized family of hypothetical acyltransferases, which had previously been linked to the PEP-CTERM/exosortase system by bioinformatics, is a new family of N-acyl amino acid synthases that is widely distributed among the PEP-CTERM/exosortase system-containing Proteobacteria.