A PHYSICAL MAP OF THE MYXOCOCCUS-XANTHUS CHROMOSOME

A physical map of the 9.2-Mbp Myxococcus xanthus DK1622 chromosome at a resolution of 25 kbp was constructed by using a strategy that is app licable to virtually all microorganisms. Segments of the chromosome we re used as hybridization probes to subdivide a yeast artificial chromo some (YAC) library into groups of linked clones. The clones were align ed by comparing their EcoRI restriction patterns. The groups of YAC cl ones (''contigs'') were oriented and aligned with the genomic restrict ion map by means of common genetic and physical markers such as rare r estriction sites and transposon insertions. Over 95% of the genome is represented by cloned DNA. Sixty genetic loci including >100 genes, ma ny of which play a role in fruiting body development, have been mapped in this way. Additional genes can now be located on the chromosome ma p by hybridization of their sequences to the ordered set of YAC chromo somes. The mapped genetic loci account for approximate to 2% of the ge nome.