The properties of NodD were affected by mere variation in length within its hinge region  

作　　者：Bihe Hou Fengqing Li Xiaoer Yang Guofan Hong 

机构地区：[1]State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai 200031, China

出　　处：《Acta Biochimica et Biophysica Sinica》2009年第11期963-971,共9页生物化学与生物物理学报（英文版）

摘　　要：In Rhizobium leguminosarum bv. viciae, NodD, a member of the LysR-type transcriptional regulators, while auto-regulating, activates transcription of other nod genes in the presence of naringenin. A hinge region of NodD was previously identified in our laboratory as a functional region independent of its N-terminal DNA-binding and C-terminal regulatory domain. Further study was carried out to see the possible effect of the length variation in the hinge region on NodD＇s properties. To our surprise, as many as seven classes of phenotypes were observed. Class Ⅰ is deficient of activating nodA transcription and abolishes auto-regulation; class Ⅱ is able to activate nodA transcription independently of naringenin and abolishes auto-regulation; class Ⅲ retains autoregulating but partial activating ability; class Ⅳ is able to activate transcription independently of naringenin and retains auto-regulation; in class Ⅴ, nodA is transcribed constitutively but the transcription level is drastically down-regulated in the presence of naringenin; in class Ⅵ, nodA is transcribed constitutively with higher induction ratio; in class Ⅶ, nodA is transcribed constitutively with lower induction ratio. To learn more about the possible mechanism, circular permutation assays were done, which showed that the length variation of the hinge of NodD caused by mutation led to the change in bend angles of nod promoter. This finding should help to get an insight into how transcriptional regulation is mediated by NodD at the molecular level as well as to understand the regulatory system of this important family.In Rhizobium leguminosarum bv. viciae, NodD, a member of the LysR-type transcriptional regulators, while auto-regulating, activates transcription of other nod genes in the presence of naringenin. A hinge region of NodD was previously identified in our laboratory as a functional region independent of its N-terminal DNA-binding and C-terminal regulatory domain. Further study was carried out to see the possible effect of the length variation in the hinge region on NodD＇s properties. To our surprise, as many as seven classes of phenotypes were observed. Class Ⅰ is deficient of activating nodA transcription and abolishes auto-regulation; class Ⅱ is able to activate nodA transcription independently of naringenin and abolishes auto-regulation; class Ⅲ retains autoregulating but partial activating ability; class Ⅳ is able to activate transcription independently of naringenin and retains auto-regulation; in class Ⅴ, nodA is transcribed constitutively but the transcription level is drastically down-regulated in the presence of naringenin; in class Ⅵ, nodA is transcribed constitutively with higher induction ratio; in class Ⅶ, nodA is transcribed constitutively with lower induction ratio. To learn more about the possible mechanism, circular permutation assays were done, which showed that the length variation of the hinge of NodD caused by mutation led to the change in bend angles of nod promoter. This finding should help to get an insight into how transcriptional regulation is mediated by NodD at the molecular level as well as to understand the regulatory system of this important family.

关 键 词：NODD hinge region circular permutation assay PHENOTYPE 

分 类 号：TH112.1[机械工程—机械设计及理论]