Structural basis for cytokinin production by LOG from Corynebacterium glutamicum.
Structural basis for cytokinin production by LOG from Corynebacterium glutamicum.
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DOI：
10.1038/srep31390
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发表时间：
2016-08-10
影响因子：
4.6
通讯作者：
Kim KJ
中科院分区：
文献类型：
--
作者：
Seo H;Kim S;Sagong HY;Son HF;Jin KS;Kim IK;Kim KJ
“孤独的家伙”（Lonely Guy）是植物和与植物相互作用的真菌中产生细胞分裂素的酶。来自土壤细菌谷氨酸棒杆菌的Cg2612的基因产物被注释为LDC。然而，C. Cg2612的氨基酸序列与Cg2612蛋白的氨基酸序列相似性较高，提示Cg2612可能是一种Cg2612蛋白。为了研究Cg2612的功能，我们以2.3 μ m的分辨率测定了它的晶体结构。Cg2612作为二聚体起作用，并显示出与其他已知LOG类似的总体结构，如来自拟南芥（Atomicopsis thaliana）、麦角菌（Claviceps purpurea）和海分枝杆菌（Mycobacterium marinum）的LOG。Cg2612还含有一个“PGGXGTXXE”基序，有助于形成类似于其他LOG的活性位点。此外，对Cg2612的生化研究表明，该蛋白具有磷酸核糖水解酶活性，但不具有LDC活性。基于这些结构和生物化学研究，我们提出Cg2612不是LDC家族酶，而是属于Cg2612家族。此外，Cg2612（Cgt3）的异戊烯基结合位点包含的残基与在Atlene和Cplene中观察到的残基相同，但与Mmlene中的残基不同。这项工作为其他微生物的LOG样蛋白提供了结构和功能上的启示。
“Lonely guy” (LOG) has been identified as a cytokinin-producing enzyme in plants and plant-interacting fungi. The gene product of Cg2612 from the soil-dwelling bacterium Corynebacterium glutamicum was annotated as an LDC. However, the facts that C. glutamicum lacks an LDC and Cg2612 has high amino acid similarity with LOG proteins suggest that Cg2612 is possibly an LOG protein. To investigate the function of Cg2612, we determined its crystal structure at a resolution of 2.3 Å. Cg2612 functions as a dimer and shows an overall structure similar to other known LOGs, such as LOGs from Arabidopsis thaliana (AtLOG), Claviceps purpurea (CpLOG), and Mycobacterium marinum (MmLOG). Cg2612 also contains a “PGGXGTXXE” motif that contributes to the formation of an active site similar to other LOGs. Moreover, biochemical studies on Cg2612 revealed that the protein has phosphoribohydrolase activity but not LDC activity. Based on these structural and biochemical studies, we propose that Cg2612 is not an LDC family enzyme, but instead belongs to the LOG family. In addition, the prenyl-binding site of Cg2612 (CgLOG) comprised residues identical to those seen in AtLOG and CpLOG, albeit dissimilar to those in MmLOG. The work provides structural and functional implications for LOG-like proteins from other microorganisms.