Primary structure and mapping of the hupA gene of Salmonella typhimurium.
In bacteria, the complex nucleoid structure is folded and maintained by negative superhelical tension and a set of type II DNA-binding proteins, also called histonelike proteins. The most abundant type II DNA-binding protein is HU. Southern blot analysis showed that Salmonella typhimurium contained two HU genes that corresponded to Escherichia coli genes hupA (encoding HU-2 protein) and hupB (encoding HU-1). Salmonella hupA was cloned, and the nucleotide sequence of the gene was determined. Comparison of hupA of E. coli and S. typhimurium revealed that the HU-2 proteins were identical and that there was high conservation of nucleotide sequences outside the coding frames of the genes. A 300-member genomic library of S. typhimurium was constructed by using random transposition of MudP, a specialized chimeric P22-Mu phage that packages chromosomal DNA unidirectionally from its insertion point. Oligonucleotide hybridization against the library identified one MudP insertion that lies within 28 kilobases of hupA; the MudP was 12% linked to purH at 90.5 min on the standard map. Plasmids expressing HU-2 had a surprising phenotype; they caused growth arrest when they were introduced into E. coli strains bearing a himA or hip mutation. These results suggest that IHF and HU have interactive roles in bacteria.
Higgins
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Department of Biochemistry, University of Alabama, Birmingham 35294.
Hillyard
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D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005798:Genes, Bacterial; D005838:Genotype; D008969:Molecular Sequence Data; D010957:Plasmids; D015183:Restriction Mapping; D012486:Salmonella typhimurium / Q000235:genetics*
D004268:DNA-Binding Proteins