The crystal structure of the cell division amidase AmiC reveals the fold of the AMIN domain, a new peptidoglycan binding domain
The crystal structure of the cell division amidase AmiC reveals the fold of the AMIN domain, a new peptidoglycan binding domain
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DOI：
10.1111/mmi.12361
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发表时间：
2013-10-01
影响因子：
3.6
通讯作者：
Kerff, Frederic
中科院分区：
文献类型：
--
作者：
Rocaboy, Mathieu;Herman, Raphael;Kerff, Frederic
二分裂是原核细胞周期的最后一步。在革兰氏阴性细菌如大肠杆菌中，这一步骤意味着三个生物层（细胞质膜、肽聚糖和外膜）的内陷、新极的生物合成以及最终子细胞的分离。后者需要N-乙酰胞壁酰-L-丙氨酸酰胺酶AmiA/B/C及其LytM激活剂EnvC和NlpD的协调作用以切割隔膜肽聚糖。我们在这里提出的2.5埃晶体结构的AmiC，其中包括AMIN域结构的第一份报告，一个三明治的两个对称的四链片暴露高度保守的基序的两个外表面。我们表明，这个N-末端结构域，参与本地化的AmiC在分裂网站，是一个新的肽聚糖结合域。C-末端催化结构域显示自身抑制性α螺旋阻碍活性位点。缺乏该螺旋的AmiC本身表现出与NlpD激活的野生型AmiC相当的活性。我们还证明了AmiC和NlpD之间的相互作用，通过微量热泳，并确认的重要性，活性位点阻断α螺旋的酰胺酶活性的调节。
Binary fission is the ultimate step of the prokaryotic cell cycle. In Gram-negative bacteria like Escherichia coli, this step implies the invagination of three biological layers (cytoplasmic membrane, peptidoglycan and outer membrane), biosynthesis of the new poles and eventually, daughter cells separation. The latter requires the coordinated action of the N-acetylmuramyl-L-alanine amidases AmiA/B/C and their LytM activators EnvC and NlpD to cleave the septal peptidoglycan. We present here the 2.5 angstrom crystal structure of AmiC which includes the first report of an AMIN domain structure, a -sandwich of two symmetrical four-stranded -sheets exposing highly conserved motifs on the two outer faces. We show that this N-terminal domain, involved in the localization of AmiC at the division site, is a new peptidoglycan-binding domain. The C-terminal catalytic domain shows an auto-inhibitory alpha helix obstructing the active site. AmiC lacking this helix exhibits by itself an activity comparable to that of the wild type AmiC activated by NlpD. We also demonstrate the interaction between AmiC and NlpD by microscale thermophoresis and confirm the importance of the active site blocking alpha helix in the regulation of the amidase activity.