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Cold-shock DEAD-box protein A (CsdA) is a DEAD-box RNA helicase in E. coli. The deaD gene encodes this CsdA protein in E. coli. It is a major cold shock protein and it plays essential roles during cold shock adaption in E. coli. CsdA homolog of E. coli is present in bacteria, archaea and eukaryotes. This major cold-shock protein has been studied at the protein level, but its mechanism of gene regulation needs further study. In this regard, we have constructed a promoter-less plasmid vector with the ORF of a GFP reporter and performed incremental zone-wise DNA scanning from the immediate upstream region of the deaD gene coding region. Interestingly, we found the promoter region about 800 nucleotides upstream of its coding region. Furthermore, the drastic decrease in CsdA protein level due to the in vivo deletion of this promoter region from the E. coli chromosome has confirmed this promoter’s existence. Interestingly, we have found this promoter region i.e., -10 region and -35 region is conserved in numbers of gammaproteobacteria. In conclusion, our study established deaD gene contains an unusually long 5'UTR of about 800 nucleotides in E. coli which is exceptional in bacteria.

Background Protein synthesis is a cellular process that takes place through the successive translation events within the ribosome by the event-specific protein factors, namely, initiation, elongation, release, and recycling factors. In this regard, we asked the question about how similar are those translation factors to each other from a wide variety of bacteria? Hence, we did a thorough in silico study of the translation factors from 495 bacterial sp., and 4262 amino acid sequences by theoretically measuring their pI and MW values that are two determining factors for distinguishing individual proteins in 2D gel electrophoresis in experimental procedures. Then we analyzed the output from various angles. Results Our study revealed the fact that it’s not all same, or all random, but there are distinct orders and the pI values of translation factors are translation event specific. We found that the translation initiation factors are mainly basic, whereas, elongation and release factors that interact with the inter-subunit space of the intact 70S ribosome during translation are strictly acidic across bacterial sp. These acidic elongation factors and release factors contain higher frequencies of glutamic acids. However, among all the translation factors, the translation initiation factor 2 (IF2) and ribosome recycling factor (RRF) showed variable pI values that are linked to the order of phylogeny. Conclusions From the results of our study, we conclude that among all the bacterial translation factors, elongation and release factors are more conserved in terms of their pI values in comparison to initiation and recycling factors. Acidic properties of these factors are independent of habitat, nature, and phylogeny of the bacterial species. Furthermore, irrespective of the different shapes, sizes, and functions of the elongation and release factors, possession of the strictly acidic pI values of these translation factors all over the domain Bacteria indicates that the acidic nature of these factors is a necessary criterion, perhaps to interact into the partially enclosed rRNA rich inter-subunit space of the translating 70S ribosome.