No abstract

The MacA–MacB–TolC tripartite complex is a transmembrane machine that spans both plasma membrane and outer membrane and actively extrudes substrates, including macrolide antibiotics, virulence factors, peptides and cell envelope precursors. These transport activities are driven by the ATPase MacB, a member of the ATP-binding cassette (ABC) superfamily. Here, we present the crystal structure of MacB at 3.4-Å resolution. MacB forms a dimer in which each protomer contains a nucleotide-binding domain and four transmembrane helices that protrude in the periplasm into a binding domain for interaction with the membrane fusion protein MacA. MacB represents an ABC transporter in pathogenic microorganisms with unique structural features.

Chorea-acanthocytosis (ChAc) is a rare autosomal recessive neurodegenerative disorder caused by loss of function mutations in the vacuolar protein sorting 13 homolog A (VPS13A) gene that encodes chorein. It is characterized by adult-onset chorea, peripheral acanthocytes, and neuropsychiatric symptoms. In the present study, we performed a comprehensive mutation screen, including sequencing and copy number variation (CNV) analysis, of the VPS13A gene in ChAc patients. All 73 exons and flanking regions of VPS13A were sequenced in 35 patients diagnosed with ChAc. To detect CNVs, we also performed real-time quantitative PCR and long-range PCR analyses for the VPS13A gene on patients in whom only a single heterozygous mutation was detected. We identified 36 pathogenic mutations, 20 of which were previously unreported, including two novel CNVs. In addition, we investigated the expression of chorein in 16 patients by Western blotting of erythrocyte ghosts. This demonstrated the complete absence of chorein in patients with pathogenic mutations. This comprehensive screen provides an accurate and useful method for the molecular diagnosis of ChAc.

No abstract

Revolver discovered in the Triticeae plant is a novel class of transposon-like gene and a major component of the large cereal genome. An 89 bp segment of Revolver that is enriched in the genome of rye was isolated by deleting the DNA sequences common to rye and wheat. The entire structure of Revolver was determined by using rye genomic clones, which were screened by the 89 bp probe. Revolver consists of 2929—3041 bp with an inverted repeated sequence on each end and is dispersed through all seven chromosomes of the rye genome. Revolver is transcriptionally active, and the isolated full-length cDNA (726 bp) reveals that Revolver harbors a single gene consisting of three exons (342, 88, and 296 bp) and two introns (750 and 1237 bp), and encodes 139 amino acid residues of protein, which shows similarity to some transcriptional regulators. Revolver variants ranging from 2665 to 4269 bp, in which 5′ regions were destructed, indicate structural diversities around the first exon. Revolver does not share identity with any known class I or class II autonomous transposable elements of any living species. DNA blot analysis of Triticeae plants shows that Revolver has existed since the diploid progenitor of wheat, and has been amplified or lost in several species during the evolution of the Triticeae.