Sequence and transcriptional activity of the Escherichia coli K-12 chromosome region between rrnC and ilvGMEDA.
We previously identified a protein related to the expression of the ilvGMEDA cluster of Escherichia coli K-12. It was observed that this ilv-related protein was produced at higher levels in UV irradiated cells infected with lambda dilvGMEDA phage with specific ilvG mutations (ValR), compared to phage carrying the wild-type(ValS) ilvG allele. The gene encoding this protein was further localized to a region between rrnC and ilvGMEDA by analyzing restriction fragment subsets in maxicells. We have now determined the nucleotide (nt) sequence of the 3.5-kb segment between rrnC and ilvGMEDA, and two open reading frames (ORFs) are present in the region expected to contain the ilv-related gene. These ORFs predicts Mrs of 18,751 (ORFI) and 20,085 (ORFII) Da, and both ORFs have a strong probability to encode proteins based on codon frequency analysis. Maxicell analysis revealed that a 1319-bp HindIII-SmaI fragment containing ORFI encodes the ilv-related peptide. We deleted a ClaI fragment that removed a portion of ORFI encoding the C-terminal region of the peptide, and maxicell analysis revealed a decrease in the size of the protein produced in accord with the prediction. RNA slot blots and Northern blots were used to characterize transcripts encoding ORFI. A transcript initiated 112 nt from the ilvGp2 promoter, but proceeding in the opposite direction, may encode the ORFI peptide.
Coppola
G
G
Department of Chemistry, City College of New York, NY 10031.
Huang
F
F
Riley
J
J
Cox
J L
JL
Hantzopoulos
P
P
Zhou
L B
LB
Calhoun
D H
DH
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003062:Codon; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D007532:Isoleucine / Q000096:biosynthesis; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014633:Valine / Q000096:biosynthesis
D001426:Bacterial Proteins; D003062:Codon; D029968:Escherichia coli Proteins; D007532:Isoleucine; D014633:Valine