Transposon Tagging to Detect a Latent Virus in Myxococcus xanthus

Abstract

Transposon mutagenesis of the bacterium Myxococcus xanthus with the transposon Tn5 revealed a special class of bacterial mutants that transduced the transposon through culture supernatant fluids. Virus-like particles copurified with transducing activity. Transposon tagging for detecting these virus-like particles may be generally useful in isolating endogenous viral agents capable of transferring genetic information between cells.

Movement of multiple DNA units between Myxococcus xanthus cells

“…Inserts to be cloned into cosmid vectors were derived from M. xanthus JZ111 to JZ120, which harbor Tn5-kan insertions at positions flJZ111 to flJZ120, respectively (13). The cosmid vector used was pmf-7, which is 5.5 kilobases (kb) in size, encodes ampicillin resistance, and bears a single EcoRI site suitable for cloning (10 packaged.…”

“…The genetic proof arose from the discovery that all of the 10 TnS transposon tags detected as transducible were genetically linked. Genetic linkage could be shown by cotransduction of the 10 tags tested pairwise in genetic crosses with Mx4, a generalized transducing phage (13). The physical map shows that each of the 10 transposon tags resides physically adjacent to certain other tags.…”

“…Recombinant DNA clones representing Mx alpha DNA sequences were derived from the cellular DNA of 10 reference bacterial strains. Each reference strain had been characterized previously by genetic analysis and had been shown to contain an independent TnS insertion transducible by Mx alpha (13). We chose to clone DNA from the cellular state, using the transducible TnS insertion as a selectable marker.…”

“…Transduction of the transposon tag was utilized in assays for purifying Mx alpha particles by their buoyant density in isopycnic density centrifugation; electron microscopy revealed that the purified particles have icosahedral symmetry (13). The particles differ from known myxophages because of their small size (30 to 35 nm) and lack of tails, but the regular particle structure and mode of transmission suggest that Mx alpha is itself a virus or has a viral origin.…”

“…Transposon tagging offers a genetic approach to detect the movement of genetic information between cells (13). In Myxococcus xanthus, a procaryotic model for development, the transposon TnS can be introduced into cells by the suicide vector Pl::TnS.…”