| Description |
A DNA-binding protein implicated in transcriptional repression (silencing) (PMID:333393, PMID:2128918, PMID:8890170, PMID:8913298, PMID:9398522, PMID:16963779, PMID:17046956, PMID:23543115). Also involved in bacterial chromosome organization and compaction (PMID:6379600, PMID:10982869, PMID:21903814). H-NS binds tightly to AT-rich dsDNA and inhibits transcription (PMID:2512122, PMID:16963779, PMID:17435766, PMID:17881364, PMID:23543115). Binds upstream and downstream of initiating RNA polymerase, trapping it in a loop and preventing transcription (PMID:11714691). Binds to hundreds of sites, approximately half its binding sites are in non-coding DNA, which only accounts for about 10% of the genome (PMID:16963779, PMID:17046956, PMID:23543115). Many of these loci were horizontally transferred (HTG); this offers the selective advantage of silencing foreign DNA while keeping it in the genome in case of need (PMID:17046956, PMID:17881364, PMID:26789284). Suppresses transcription at many intragenic sites as well as transcription of spurious, non-coding RNAs genome-wide (PMID:24449106). Repression of HTG by H-NS is thought to allow their DNA to evolve faster than non-H-NS-bound regions, and facilitates integration of HTG into transcriptional regulatory networks (PMID:26789284). A subset of H-NS/StpA-regulated genes also require Hha (and/or Cnu, ydgT) for repression; Hha and Cnu increase the number of genes DNA bound by H-NS/StpA and may also modulate the oligomerization of the H-NS/StpA-complex (PMID:23543115). The protein forms 2 clusters in the nucleoid which gather hns-bound loci together, bridging non-contiguous DNA, and causes DNA substantial condensation (PMID:21903814). Binds DNA better at low temperatures than at 37 degrees Celsius; AT-rich sites nucleate H-NS binding, further DNA-binding is cooperative and this cooperativity decreases with rising temperature (PMID:17435766, PMID:17881364). Transcriptional repression can be inhibited by dominant-negative mutants of StpA or itself (PMID:8755860). May effect transcriptional elongation (PMID:25638302). Can increase translational efficiency of mRNA with suboptimal Shine-Dalgarno sequences (PMID:20595230). Plays a role in the thermal control of pili and adhesive curli fimbriae production, by inducing transcription of csgD (PMID:17010156). Plays a role in flagellar function (PMID:11031114). Represses the CRISPR-cas promoters, permits only weak transcription of the crRNA precursor; its repression is antagonized by LeuO (PMID:20132443, PMID:20659289). Binds preferentially to the upstream region of its own gene recognizing two segments of DNA on both sides of a bend centered around -150 (PMID:7934818). Overexpression suppresses secY24, a temperature-sensitive mutation (PMID:1537791). Has also been reported to activate transcription of some genes (PMID:4566454, PMID:338303, PMID:2128918). |
| Other names |
DNA-binding protein H-NS, Heat-stable nucleoid-structuring protein, Histone-like protein HLP-II, Protein B1, Protein H1, hns, bglY, cur, drdX, hnsA, msyA, osmZ, pilG, topS |
