Update on cpnDB: a reference database of chaperonin sequences

cpnDB was established in 2004 to provide a manually curated database of type I (60 kDa chaperonin, CPN60, also known as GroEL or HSP60) and type II (CCT, TRiC, thermosome) chaperonin sequences and to support chaperonin sequence-based applications including microbial species identification, detection and quantification, phylogenetic investigations and microbial community profiling. Since its establishment, cpnDB has grown to over 25 000 sequence records including over 4 000 records from bacterial type strains. The updated cpnDB webpage (www.cpndb.ca) provides tools for text- or sequence-based searches and links to protocols, and selected reference data sets are available for download. Here we present an updated description of the contents and taxonomic coverage of cpnDB and an analysis of cpn60 sequence diversity.