1984 Abst. Amer. Soc. Microbiol., St. Louis, MO

Repetitive DNA Sequences in the Genome of the Archaebacterial Methanogen, Methanobrevibacter smithii.

PAUL T. HAMILTON*, JAMES W. BROWN and JOHN N. REEVE

Dept. Microbiology, The Ohio State University, Columbus, OH 43210

A 2.4Kb EcoRI/HindIII DNA fragment from M. smithii has been cloned into pBF322. The recombinant plasmid, designated pET417, complements E. coli proC mutations. Tn5 insertions in pET417 have been used to delineate the region of M. smithii DNA in pET417 responsible for proC complementation. DNA:DNA hybridizations using radioactively labeled pET417 to probe digests of M . smithii DNA indicate that there is a sequence on pET417 which is present in 7 to 10 copies per M. smithii genome. Subcloning from pET417 has demonstrated that the DNA encoding the proC complementing activity and the repetitive DNA not necessary for expression of the proC complementing activity in E. coli. The repeated DNA sequence appears to be involved in rearrangements of the M. smithii genome. DNA isolated from cultures of IM. smithii, grown for different numbers of generations, have different DNA:DNA hybridization patterns when probed with pET417. DNA sequence determination has shown that the M. smithii DNA in pET417 has a very low GC content consistent with the known low GC content of total DNA from M. smithii.