Hirschsprung disease (HSCR) is sometimes associated with a set of characteristics including mental retardation, microcephaly, and distinct facial features, but the gene mutated in this condition has not yet been identified. Here we report that mutations in SIP1, encoding Smad interacting protein-1, cause disease in a series of cases. SIP1 is located in the deleted segment at 2q22 from a patient with a de novo t(2;13)(q22;q22) translocation. SIP1 seems to have crucial roles in normal embryonic neural and neural crest development.

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The nucleotide sequence of the ompF gene coding for a major outer membrane protein of Escherichia coli K-12 has been determined and the amino acid sequence of the OmpF protein was deduced from it. The OmpF protein contains 340 amino acid residues, and is produced from a precursor having 22 extra amino acid residues, the signal peptide, at the amino terminus. The expected secondary structure of the OmpF protein had a high beta-sheet content with a low alpha-helix content. The promoter region and the transcription termination region of the ompF gene had a significantly high AT content, while the AT content of the coding region was about the same as the average AT content of the E. coli chromosome. Following the termination codon, a typical rho-independent transcription termination signal was observed. The codon usage in the ompF gene was highly nonrandom; the codons preferably utilized are those recognized by the most abundant species of isoaccepting tRNAs or those, among synonymous codons recognized by the same tRNA, that can interact more properly with the anticodon.

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The nucleotide sequence of DNA which contains five chemotaxis-related genes of Escherichia coli, cheW, cheR, cheB, cheY, and cheZ, and part of the cheA gene was determined. Molecular weights of the polypeptides encoded by these genes were calculated from translated amino acid sequences, and they were 18,100 for cheW, 32,700 for cheR, 37,500 for cheB, 14,100 for cheY, and 24,000 for cheZ. Nucleotide sequences which could act as ribosome-binding sites were found in the upstream region of each gene. After the termination codon of the cheW gene, a typical rho-independent transcription termination signal was observed. There are no other open reading frames long enough to encode polypeptides in this region except those which code for the two previously reported genes tar and tap.Many of the genes that are required for bacterial chemotaxis have been identified, and their gene products have been characterized in both Escherichia coli and Salmonella typhimurium (1,4,10,12,17,22). Two operons that are adjacent to each other on the bacterial genome encode 10 chemotaxis-related functions. The Mocha operon includes the motA and motB genes that are responsible for coupling flagella rotation to energy supplied by the electrochemical gradient across the cell membrane. Adjacent to these genes are the cheA and cheW genes that are required for chemotaxis (1, 12, 17). The second operon includes the tar and tap genes, which are responsible for the synthesis of transmembrane receptor proteins (2, 7), the cheR and cheB genes, which reversibly methylate the transmembrane proteins and are responsible for adaptation (5,20,23), and the che Y and cheZ genes, which are thought to play a central role in generating a signal that regulates bacterial flagella rotation (1,3,12,15,17). In the past 10 years, we have learned how to measure and analyze components of the chemotaxis system in a variety of sophisticated ways; however, we still do not understand the basis for the signal transduction process, i.e., how the binding of a specific attractant molecule to a receptor generates a signal that regulates flagellar rotation. One approach to this problem involves the manipulation of the levels of the chemotaxis gene products and the isolation and purification of the gene products to study their biochemical properties. This approach would be greatly facilitated by the availability of the nucleic acid sequence of the genes responsible for chemotaxis. The tar and tap gene sequences have been published (8). In this paper, we report the DNA sequence and the derived amino sequences for the cheW, cheR, cheB, cheY, and cheZ genes and for part of the cheA gene. MATERIALS AND METHODSEnzymes and chemicals. All restriction enzymes used in this study were purchased from Bethesda Research Laboratories, Inc., and New England BioLabs, Inc. T4 DNA ligase was obtained from Bethesda Research Laboratories. M13-mp7 replicative-form DNA was from Bethesda Research Labora-* Corresponding author. tories, and M13-mp8 and M13-mp9 were purchased from P-L Biochemicals, Inc. Did...