Disease relevance of orfX

• When orfX was expressed from a phage T7 promoter in E. coli, a protein with an apparent molecular mass of approximately 18 kDa was produced [1].
• The first, orfX, is predicted to encode a 105-amino-acid polypeptide that is similar to MopB, a protein which is required for both motility and virulence in Erwinia carotovora [2].
• The N-terminus of the ORFs is similar to a putative glycoprotease in Pasteurella haemolytica and its homologue in Escherichia coli, the orfX gene [3].
• The smaller open reading frame, orfX, also observed in Streptomyces coelicolor and Streptomyces avermitilis, may be translationally coupled to pnp and the gene downstream from pnp, a putative protease [4].

High impact information on orfX

• Disruption of orfX had no effect on growth but caused a sporulation defect, characterized by low sporulation frequencies and heat-sensitive spores, which could be cured by supplementation with dipicolinate, similar to the phenotype of mutants defective in spoVF, the putative structural gene for dipicolinate synthase [5].
• The orfX gene product was shown not to be directly linked to the lysine biosynthetic pathway, nor is it the enzyme incorporating DAP into the peptidoglycan precursor [6].
• Through the use of transcriptional fusions, none of the putative tol (or tol-associated) genes were shown to be regulated by PhoPQ, bile, or the RcsC-RcsB two-component system; however, all of the genes (orfX, orf1, tolQRA) are predicted to be cotranscribed [7].
• Via the N-terminal amino-acid sequence, the MtdB encoding gene was identified to be orfX located in a cluster of genes whose translated products show high sequence identities to enzymes previously found only in methanogenic and sulfate reducing archaea [8].
• Reverse transcriptase-PCR analysis indicated that flbF through to orfX are transcribed as a single mRNA, and primer extension analysis revealed that transcription of the flgK operon is initiated by a sigma 70-like promoter upstream of flbF [9].

Chemical compound and disease context of orfX

• The deduced products of four of these ORFs were homologous to components of the glucitol phosphotransferase system (PTS) and glucitol 6-phosphate dehydrogenase from E. coli, while the remaining ORF (orfX) encoded an enzyme which had similarities to members of a family of transaldolases [10].

Biological context of orfX

• Nucleotide sequence analysis of the region 5' to vfr identified a 423-bp open reading frame (ORF), which was designated orfX [1].
• The transcriptional start point determined by primer extension analysis suggested that -10 and -35 regions are present upstream of orfX and are very similar to the consensus sequence for the sigma k-dependent promoter [11].
• The latter consists of two monocistronic operons gtaB and orfX, transcribed from a 245 bp regulatory region, each encoding an acidic protein with a molecular mass of 33.0 and 42.6 kDa, respectively. gtaB is transcribed from a distal PA promoter, and a proximal PB promoter which is negatively controlled by the Sin protein [12].

References