Format

Send to

Choose Destination
See comment in PubMed Commons below
J Bacteriol. 2005 Nov;187(21):7176-84.

A hypervariable 130-kilobase genomic region of Magnetospirillum gryphiswaldense comprises a magnetosome island which undergoes frequent rearrangements during stationary growth.

Author information

1
MPI für Marine Mikrobiologie, Celsiusstr. 1, 28359 Bremen, Germany.

Abstract

Genes involved in magnetite biomineralization are clustered in the genome of the magnetotactic bacterium Magnetospirillum gryphiswaldense. We analyzed a 482-kb genomic fragment, in which we identified an approximately 130-kb region representing a putative genomic "magnetosome island" (MAI). In addition to all known magnetosome genes, the MAI contains genes putatively involved in magnetosome biomineralization and numerous genes with unknown functions, as well as pseudogenes, and it is particularly rich in insertion elements. Substantial sequence polymorphism of clones from different subcultures indicated that this region undergoes frequent rearrangements during serial subcultivation in the laboratory. Spontaneous mutants affected in magnetosome formation arise at a frequency of up to 10(-2) after prolonged storage of cells at 4 degrees C or exposure to oxidative stress. All nonmagnetic mutants exhibited extended and multiple deletions in the MAI and had lost either parts of or the entire mms and mam gene clusters encoding magnetosome proteins. The mutations were polymorphic with respect to the sites and extents of deletions, but all mutations were found to be associated with the loss of various copies of insertion elements, as revealed by Southern hybridization and PCR analysis. Insertions and deletions in the MAI were also found in different magnetosome-producing clones, indicating that parts of this region are not essential for the magnetic phenotype. Our data suggest that the genomic MAI undergoes frequent transposition events, which lead to subsequent deletion by homologous recombination under physiological stress conditions. This can be interpreted in terms of adaptation to physiological stress and might contribute to the genetic plasticity and mobilization of the magnetosome island.

PMID:
16237001
PMCID:
PMC1272989
DOI:
10.1128/JB.187.21.7176-7184.2005
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center