Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel.
Res Microbiol. 2013 Jan;164(1):12-6. doi: 10.1016/j.resmic.2012.10.005. Epub 2012 Oct 17.
Here we characterize the first step in methionine biosynthesis in Agrobacterium tumefaciens, an α-proteobacterium. We explored the metA gene and its products and found several unique properties. Although the gene was annotated as a homoserine transsuccinylase, based upon sequence similarity to characterized homologs in other bacteria, including Escherichia coli, the enzyme uses acetyl-CoA as a substrate and therefore is functionally a transacetylase. Moreover, the protein is thermolabile and the gene is under regulation of heat shock transcriptional activator σ32. 3. The gene has a SAM-riboswitch, which shuts off transcription by σ-32 as well as by the vegetative σ-70.
在这里，我们描述了根瘤农杆菌（一种α-变形菌）中蛋氨酸生物合成的第一步。我们研究了 metA 基因及其产物，发现了一些独特的性质。尽管该基因被注释为同型丝氨酸转琥珀酰酶，但根据与其他细菌（包括大肠杆菌）中已鉴定的同源物的序列相似性，该酶使用乙酰辅酶 A 作为底物，因此在功能上是一种转乙酰酶。此外，该蛋白热不稳定，基因受热休克转录激活因子σ32 的调控。该基因有一个 SAM-riboswitch，它可以关闭σ-32 和营养型σ-70 的转录。
