In bacteria, signaling phosphorylation is thought to occur primarily on His and Asp residues. However, phosphoproteomic surveys in phylogenetically diverse bacteria over the past decade have identified numerous proteins that are phosphorylated on Ser and/or Thr residues. Consistently, genes encoding Ser/Thr kinases are present in many bacterial genomes such as in the Escherichia coli genome, which encodes at least three Ser/Thr kinases. Here, we identify a previously uncharacterized ORF, yegI, and demonstrate that it encodes a novel Ser/Thr kinase. YegI lacks several conserved motifs including residues important for Mg2+ binding seen in other bacterial Ser/Thr kinases, suggesting that the consensus may be too stringent. We further find that YegI is a two‐pass membrane protein with both N‐ and C termini located intracellularly.

中文翻译：

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大肠杆菌 YegI 是一种新型 Ser/Thr 激酶，缺乏定位于内膜的保守基序

在细菌中，信号磷酸化被认为主要发生在 His 和 Asp 残基上。然而，过去十年对系统发育不同细菌的磷酸化蛋白质组学调查已经确定了许多在 Ser 和/或 Thr 残基上磷酸化的蛋白质。一致地，编码丝氨酸/苏氨酸激酶的基因存在于许多细菌基因组中，例如编码至少三种丝氨酸/苏氨酸激酶的大肠杆菌基因组。在这里，我们确定了以前未表征的 ORF，yegI，并证明它编码一种新型 Ser/Thr 激酶。YegI 缺乏几个保守的基序，包括在其他细菌 Ser/Thr 激酶中看到的对 Mg2+ 结合很重要的残基，这表明共识可能过于严格。我们进一步发现，YegI 是一种双通道膜蛋白，N 端和 C 端都位于细胞内。