Abstract
The Mycoplasma pneumoniae cytadhesin P1 structural gene with flanking regions was labeled by nick translation and used as a probe to analyze gene copy number in M. pneumoniae. Multiple bands of genomic DNA were hybridized by the probe. To establish what part of the P1 gene existed as multiple copies, the P1 gene and regions adjacent to the 3' and 5' ends were divided with restriction enzymes into 14 segments ranging in size from 174 to 651 base pairs. These pieces were purified on agarose gels, subcloned into pUC19, purified, labeled by nick translation, and used to probe the entire M. pneumoniae genome. Several regions near the middle and carboxy end of the P1 structural gene hybridized to single copies. The remaining P1 subclones hybridized to multiple bands under stringent hybridization conditions, indicating extensive homology with other parts of the M. pneumoniae genome. The single- versus multiple-copy nature of P1 structural gene domains is discussed.