Investigating the role of rrf2 genes: nsrR and rsrR in S. coelicolor and S. venezuelae.

Munnoch, John (2016) Investigating the role of rrf2 genes: nsrR and rsrR in S. coelicolor and S. venezuelae. Doctoral thesis, University of East Anglia.

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This thesis furthers work on and identifies two Rrf2 regulators with distinct biochemistry
and regulons involved in redox homeostasis in S. coelicolor and S. venezuelae.
Members of the Rrf2 superfamily of transcription factors are widespread in bacteria and
have a range of known regulatory functions including sensing and responding to nitric
oxide stress, iron limitation, cysteine availability and the iron sulfur cluster status of the
cell. Here we report further study of the Rrf2 protein named NsrR and the identification
and characterisation of a novel putative redox sensor RsrR in S. coelicolor and S.
venezuelae respectively.
NsrR is a global regulator in a range of bacteria, controlling gene expression of a diverse
regulon (~35 to >60 genes in B. subtilis and E. coli, respectively) in response to nitrogen
stress through a [4Fe-4S] co-factor. We show through ChIP-seq and in vitro DNA-binding
studies that NsrR controls only hmpA1, hmpA2 and nsrR by binding to a 11-bp inverted
repeat sequence upstream of each gene. Hmp is an NO-detoxifying flavohemoglobin,
indicating that NsrR contains a specialised regulon responsible for NO detoxification. We
also report an NsrR-independent, NO dependent delay of sporulation in S. coelicolor
through an unknown route.
RsrR, encoded by a diverse group of actinomycetes, contains an oxygen stable, putative
redox-sensing [2Fe-2S] cluster that cycles between an oxidised and reduced state. ChIPseq
suggests RsrR binds strongly to an 11-3-11bp inverted repeat to, at least, 16 target
sites and more weakly to an 11bp half site at the remaining >100 targets while dRNA-seq
indicates a distinctly different set of targets while suggesting the main function of RsrR is
regulation of the sven6562 (nmrA) gene, which is transcribed divergently from RsrR.
NmrA is a putative LysR-type regulator containing a C-terminal DNA-binding domain and
an N-terminal NmrA domain that we hypothesis senses redox poise by binding NAD(P)+
but not NAD(P)H.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Users 4971 not found.
Date Deposited: 25 May 2017 14:11
Last Modified: 25 May 2017 14:11


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