Disease relevance of SIGB

• The recombinant SIG2 protein mixed with Escherichia coli core RNA polymerase could bind to a DNA fragment that contains the SIG2-dependent psbD -256, trnE-UUC or trnV-UAC promoter [1].

High impact information on SIGB

• We have cloned three distinct cDNAs, designated SIG1, SIG2, and SIG3, for polypeptides possessing amino acid sequences for domains conserved in sigma70 factors of bacterial RNA polymerases from the higher plant Arabidopsis thaliana [2].
• Characterization of Arabidopsis plastid sigma-like transcription factors SIG1, SIG2 and SIG3 [3].
• Surprisingly, this phenotype is different from the phenotype of SIG2 knockout plants in that the chlorophyll deficiency is limited to cotyledons [3].
• SIG2 is present as a soluble factor while SIG3 is partly attached to the plastid membranes [3].
• DNA microarray analysis of plastid gene expression in an Arabidopsis mutant deficient in a plastid transcription factor sigma, SIG2 [4].

Biological context of SIGB

• Transient expression assays using green fluorescent protein demonstrated that N-terminal regions of the SIG2 and SIG3 ORFs could function as transit peptides for import into chloroplasts [2].
• Only SIG2 anti-sense plants show a visible phenotype characterized by chlorophyll deficiency [3].
• In this study, we constructed a DNA microarray for all of the plastid protein-coding genes, and analyzed the effects of the sig2 lesion on the global plastid gene expression [4].
• Sequences similar to those of the -35 and -10 promoter elements of E.coli were identified in the regions of the SIG2-dependent chloroplast genes upstream of the transcription initiation sites [1].
• The abundance of these transcripts was restored to wild-type levels by introduction into the mutant of a SIG2 transgene [1].

Associations of SIGB with chemical compounds

• Two of the maize cDNAs, sig1 and sig3, encode NH2-terminal transit peptides which direct the uptake of a heterologous protein into chloroplasts in vitro [5].

References