BacS: An Abundant Bacteroid Protein in \u3cem\u3eRhizobium etli\u3c/em\u3e Whose Expression Ex Planta Requires \u3cem\u3enifA\u3c/em\u3e

Rhizobium etli CFN42 bacteroids from bean nodules possessed an abundant 16-kDa protein (BacS) that was found in the membrane pellet after cell disruption. This protein was not detected in bacteria cultured in tryptone-yeast extract. In minimal media, it was produced at low oxygen concentration but not in a mutant whose nifA was disrupted. N-terminal sequencing of the protein led to isolation of a bacS DNA fragment. DNA hybridization and nucleotide sequencing revealed three copies of the bacS gene, all residing on the main symbiotic plasmid of strain CFN42. A stretch of 304 nucleotides, exactly conserved upstream of all three bacS open reading frames, had very close matches with the NifA and sigma 54 consensus binding sequences. The only bacS homology in the genetic sequence databases was to three hypothetical proteins of unknown function, all from rhizobial species. Mutation and genetic complementation indicated that each of the bacS genes gives rise to a BacS polypeptide. Mutants disrupted or deleted in all three genes did not produce the BacS polypeptide but were Nod+ and Fix+ on Phaseolus vulgaris

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead