Novel structural features drive DNA binding properties of Cmr, a CRP family protein in TB complex mycobacteria.
Novel structural features drive DNA binding properties of Cmr, a CRP family protein in TB complex mycobacteria.
复制标题
DOI：
10.1093/nar/gkx1148
复制
发表时间：
2018-01-09
影响因子：
14.9
通讯作者：
McDonough KA
中科院分区：
文献类型：
--
作者：
Ranganathan S;Cheung J;Cassidy M;Ginter C;Pata JD;McDonough KA
结核分枝杆菌（Mtb）编码两个CRP/FNR家族转录因子（TF）， Cmr （Rv1675c）和CRPMt （Rv3676）参与毒力。先前的研究发现，尽管每个TF识别重叠的DNA基序，但它们的染色体结合谱不同。目前的研究表明，Cmr的结合特异性是由基序位置4和13的鉴别核苷酸决定的。x射线晶体学和靶向突变分析发现了一个富含精氨酸的环，该环扩展了Cmr的DNA相互作用，超出了所有CRP/FNR家族成员常见的经典螺旋-螺旋-螺旋接触，并促进了与不完美DNA序列的结合。Cmr与DNA的结合导致DNA明显的不对称弯曲，其高水平的协同性与DNA促进的二聚化一致。一个独特的n端延伸插入DNA结合和二聚化结构域之间，部分封锁了发现典型cAMP结合口袋的位点。然而，该n端的非结构化区域可能有助于调节Cmr活性以响应细胞信号。Cmr的多水平DNA相互作用可能增强了其整合多种基因调控信号的能力，而其新颖的结构特征使Cmr成为非典型的CRP/FNR家族成员。
Mycobacterium tuberculosis (Mtb) encodes two CRP/FNR family transcription factors (TF) that contribute to virulence, Cmr (Rv1675c) and CRPMt (Rv3676). Prior studies identified distinct chromosomal binding profiles for each TF despite their recognizing overlapping DNA motifs. The present study shows that Cmr binding specificity is determined by discriminator nucleotides at motif positions 4 and 13. X-ray crystallography and targeted mutational analyses identified an arginine-rich loop that expands Cmr’s DNA interactions beyond the classical helix-turn-helix contacts common to all CRP/FNR family members and facilitates binding to imperfect DNA sequences. Cmr binding to DNA results in a pronounced asymmetric bending of the DNA and its high level of cooperativity is consistent with DNA-facilitated dimerization. A unique N-terminal extension inserts between the DNA binding and dimerization domains, partially occluding the site where the canonical cAMP binding pocket is found. However, an unstructured region of this N-terminus may help modulate Cmr activity in response to cellular signals. Cmr’s multiple levels of DNA interaction likely enhance its ability to integrate diverse gene regulatory signals, while its novel structural features establish Cmr as an atypical CRP/FNR family member.
登录
查看更多内容
影响因子：
2.8
作者：
Agarwal, Nisheeth;Raghunand, Tirumalai R.;Bishai, William R.
通讯作者：
Bishai, William R.
影响因子：
14.9
作者：
EBRIGHT, RH;EBRIGHT, YW;GUNASEKERA, A
通讯作者：
GUNASEKERA, A
影响因子：
14.9
作者：
ASLANIDIS, C;DEJONG, PJ
通讯作者：
DEJONG, PJ
影响因子：
64.8
作者：
GARTENBERG, MR;CROTHERS, DM
通讯作者：
CROTHERS, DM
影响因子：
4.8
作者：
Fekete, RA;Frost, LS
通讯作者：
Frost, LS