RESUMO
Since previous interspecies comparisons of Caulobacter genomes have revealed extensive genome rearrangements, we decided to compare the nucleotide sequences of four C. crescentus genomes, NA1000, CB1, CB2, and CB13. To accomplish this goal, we used PacBio sequencing technology to determine the nucleotide sequence of the CB1, CB2, and CB13 genomes, and obtained each genome sequence as a single contig. To correct for possible sequencing errors, each genome was sequenced twice. The only differences we observed between the two sets of independently determined sequences were random omissions of a single base in a small percentage of the homopolymer regions where a single base is repeated multiple times. Comparisons of these four genomes indicated that horizontal gene transfer events that included small numbers of genes occurred at frequencies in the range of 10-3 to 10-4 insertions per generation. Large insertions were about 100 times less frequent. Also, in contrast to previous interspecies comparisons, we found no genome rearrangements when the closely related NA1000, CB1, and CB2 genomes were compared, and only eight inversions and one translocation when the more distantly related CB13 genome was compared to the other genomes. Thus, we estimate that inversions occur at a rate of one per 10 to 12 million generations in Caulobacter genomes. The inversions seem to be complex events that include the simultaneous creation of indels.
Assuntos
Caulobacter crescentus/genética , Inversão Cromossômica , Transferência Genética Horizontal , Genoma Bacteriano , Caulobacter crescentus/isolamento & purificação , Mapeamento Cromossômico , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Mutação INDEL , Mutagênese Insercional , Sequenciamento Completo do GenomaRESUMO
The complete genome sequence of Caulobacter vibrioides strain CB1 consists of a chromosome of 4,137,285 bp, with a GC content of 67.2% and 3,990 coding DNA sequences. This strain contains the typical genome rearrangement that is characteristic of the Caulobacter strains that are currently sequenced. However, this strain is so closely related to sequenced strain NA1000 that rearrangements were minimal. This will allow further clarification of the causes of rearrangements in the species.
RESUMO
The complete genome of Caulobacter vibrioides strain CB2 consists of a 4,123,726-bp chromosome, a GC content of 67.2%, and 3,896 coding DNA sequences. It has no rearrangements but numerous indels relative to the reference NA1000 genome. This will allow us to study the impact of horizontal gene transfer on caulobacter genomes.
