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Gene Review:

orfA - hypothetical protein

Escherichia coli

Vrijbloed, J.W. et al., Wong, J. et al., Polard, P. et al., Takagi, M. et al., Kersulyte, D. et al., et al.

Bralley, Jones,

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Disease relevance of orfA

No clear similarities were found between the deduced amino acid sequences of the putative orfA and orfB products of pMEA300 and replication proteins identified for various Streptomyces plasmids [1].
Mutational tests showed that its transposition in E. coli required orfA but not orfB, suggesting that OrfA protein may represent a new, previously unrecognized, family of bacterial transposases [2].
Three sporulation-specific genes (orfA, sigE, sigG) from clostridium acetobutylicum ATCC 824 are arranged in a cluster, encoding the putative sigma E-processing enzyme, sigma E, and sigma sigma G respectively [3].

High impact information on orfA

Sequence analysis of the 2.6 kb fragment revealed at least two open reading frames, orfA and orfB, encoding putative proteins of 170 amino acids (18,373 Da) and 416 amino acids (45,260 Da), respectively [1].
The 42 kDa protein is a transframe protein (here called OrfB), which is synthesized from orfA and orfB by -1 translational frameshifting at the A4G motif present in the overlapping region [4].
A larger protein, ORFAB, uses the same initiation codon and is produced by a -1 programmed translational frameshift between orfA and a downstream frame, orfB, whose amino acid sequence shows significant homology with retroviral integrase proteins [5].
The larger of these, orfA, may be a pseudogene [6].
The three genes were shown to constitute an operon transcribed in the direction orfA-pyrH-frr1 from a promoter immediately in front of orfA [7].

Biological context of orfA

By primer extension analysis, a major heat-inducible transcription start site was identified 49 bases upstream of orfA [8].
Genetic analyses indicated that orfA probably is naturally frame-shifted and does not contribute to the Asd phenotype [9].
Three kinds of recombinations were then attempted with nonreplicative plasmids: duplication of orfA and sigE, replacement of all of the three genes, and inactivation of orfA [3].

Associations of orfA with chemical compounds

Sequence analysis of the flanking regions of the hmgr gene revealed five new open reading frames, orfA to -E, which showed similarity to those encoding eucaryotic and archaebacterial enzymes for the mevalonate pathway [10].

References

Identification of the minimal replicon of plasmid pMEA300 of the methylotrophic actinomycete Amycolatopsis methanolica. Vrijbloed, J.W., Jelínková, M., Hessels, G.I., Dijkhuizen, L. Mol. Microbiol. (1995) [Pubmed]
Functional organization and insertion specificity of IS607, a chimeric element of Helicobacter pylori. Kersulyte, D., Mukhopadhyay, A.K., Shirai, M., Nakazawa, T., Berg, D.E. J. Bacteriol. (2000) [Pubmed]
Recombination-induced variants of Clostridium acetobutylicum ATCC 824 with increased solvent production. Wong, J., Bennett, G.N. Curr. Microbiol. (1996) [Pubmed]
Translational control in production of transposase and in transposition of insertion sequence IS3. Sekine, Y., Eisaki, N., Ohtsubo, E. J. Mol. Biol. (1994) [Pubmed]
Programmed translational frameshifting and initiation at an AUU codon in gene expression of bacterial insertion sequence IS911. Polard, P., Prère, M.F., Chandler, M., Fayet, O. J. Mol. Biol. (1991) [Pubmed]
Organization and expression of the polynucleotide phosphorylase gene (pnp) of Streptomyces: Processing of pnp transcripts in Streptomyces antibioticus. Bralley, P., Jones, G.H. J. Bacteriol. (2004) [Pubmed]
The pyrH gene of Lactococcus lactis subsp. cremoris encoding UMP kinase is transcribed as part of an operon including the frr1 gene encoding ribosomal recycling factor 1. Wadskov-Hansen, S.L., Martinussen, J., Hammer, K. Gene (2000) [Pubmed]
Molecular characterization of the dnaK gene region of Clostridium acetobutylicum, including grpE, dnaJ, and a new heat shock gene. Narberhaus, F., Giebeler, K., Bahl, H. J. Bacteriol. (1992) [Pubmed]
Molecular genetic analysis of the region containing the essential Pseudomonas aeruginosa asd gene encoding aspartate-beta-semialdehyde dehydrogenase. Hoang, T.T., Williams, S., Schweizer, H.P., Lam, J.S. Microbiology (Reading, Engl.) (1997) [Pubmed]
A gene cluster for the mevalonate pathway from Streptomyces sp. Strain CL190. Takagi, M., Kuzuyama, T., Takahashi, S., Seto, H. J. Bacteriol. (2000) [Pubmed]

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