Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany.
Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany.
Environ Microbiol. 2023 Nov;25(11):2416-2430. doi: 10.1111/1462-2920.16471. Epub 2023 Jul 31.
The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L-arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α-ketoglutarate. Molecular, genetic, and biochemical experiments revealed one branch to be specific for L-arabonate oxidation, and the other for D-xylonate and D-ribonate. Both clusters also encode an uptake system and a regulator that acts as activator (L-arabonate) or repressor (D-xylonate and D-ribonate). Genes encoding the initial oxidation of pentose to pentonate were not part of the clusters, but our data are consistent with the hypothesis of a promiscous, pyrroloquinoline quinone (PQQ)-dependent, periplasmic pentose dehydrogenase, followed by the uptake of the pentonates and their degradation by specific pathways. However, there is a cross-talk between the two different pathways since the isoenzymes can replace each other. Growth on pentoses was found only in pathogenic Acinetobacter species but not in non-pathogenic such as Acinetobacter baylyi. However, mutants impaired in growth on pentoses were not affected in traits important for infection, but growth on L-arabinose was beneficial for long-term survival and desiccation resistance in A. baumannii ATCC 19606.
医院病原体鲍曼不动杆菌以其非凡的代谢多样性而闻名。最近，我们证明了它可以在 L-阿拉伯糖上生长，但该途径仍然难以捉摸。转录组分析显示，有两个上调的基因簇，它们编码同工酶，可将戊糖氧化为α-酮戊二酸。分子、遗传和生化实验表明，一个分支专门用于 L-阿拉伯酸盐的氧化，另一个分支用于 D-木糖酸盐和 D-核糖酸盐。这两个簇还编码一个摄取系统和一个调节剂，作为激活剂（L-阿拉伯酸盐）或抑制剂（D-木糖酸盐和 D-核糖酸盐）。编码戊糖初始氧化为戊糖的基因不是簇的一部分，但我们的数据与一个混杂的、吡咯喹啉醌 (PQQ) 依赖的、周质戊糖脱氢酶的假设一致，然后是戊糖的摄取及其通过特定途径的降解。然而，由于同工酶可以相互替代，因此两种不同的途径之间存在交叉对话。只有致病性鲍曼不动杆菌物种能够在戊糖上生长，而非致病性的如鲍曼不动杆菌 baylyi 则不能。然而，在戊糖生长中受损的突变体在感染的重要特征方面不受影响，但在 L-阿拉伯糖上的生长对 A.baumannii ATCC 19606 的长期存活和干燥抗性有益。
