In:
Microbial Physiology, S. Karger AG, Vol. 21, No. 3-4 ( 2011), p. 147-159
Abstract:
〈 i 〉 Azotobacter vinelandii 〈 /i 〉 is a soil bacterium that produces the polysaccharide alginate. The two-component system GacS/GacA is required for alginate synthesis since a mutation in 〈 i 〉 gacS 〈 /i 〉 or 〈 i 〉 gacA 〈 /i 〉 significantly reduced the level of transcripts of 〈 i 〉 algD 〈 /i 〉 , the gene encoding GDP-mannose dehydrogenase, a key enzyme of the alginate biosynthetic pathway. In many γ-proteobacteria, GacA homologs control the expression of small regulatory RNAs of the RsmZ/Y/X (CsrB/CsrC) family that interact with RsmA (CsrA) proteins. These proteins bind to their target mRNAs acting as translational repressors. The interaction of Rsm/Csr small RNAs with RsmA/CsrA counteract its repressor activity. In this study, one 〈 i 〉 rsmA 〈 /i 〉 gene, seven 〈 i 〉 rsmZ 〈 /i 〉 and two 〈 i 〉 rsmY 〈 /i 〉 homologs were identified in the 〈 i 〉 A. vinelandii 〈 /i 〉 genome. Two of the 〈 i 〉 rsmZ 〈 /i 〉 homologs, named 〈 i 〉 rsmZ1 〈 /i 〉 and 〈 i 〉 rsmZ2 〈 /i 〉 , together with 〈 i 〉 rsmA 〈 /i 〉 , were characterized. Northern blot analysis was carried out to show that in 〈 i 〉 A. vinelandii, 〈 /i 〉 GacA activates 〈 i 〉 rsmZ1 〈 /i 〉 and 〈 i 〉 rsmZ2 〈 /i 〉 transcription. We also showed that either overexpression of 〈 i 〉 rsmA 〈 /i 〉 or inactivation of 〈 i 〉 rsmZ1 〈 /i 〉 or 〈 i 〉 rsmZ2 〈 /i 〉 diminished the production of alginate. In addition, interaction of RsmA with RsmZ1, RsmZ2 and the 〈 i 〉 algD 〈 /i 〉 mRNA was demonstrated in vitro. These results show that GacS/A regulates alginate biosynthesis by post-transcriptional control of 〈 i 〉 algD 〈 /i 〉 expression through the Rsm system.
Type of Medium:
Online Resource
ISSN:
2673-1665
,
2673-1673
Language:
English
Publisher:
S. Karger AG
Publication Date:
2011
detail.hit.zdb_id:
3042601-7
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