Oral Session
S1 Genetics and Molecular Biology
January 19, Monday
Morning session (09:00〜11:55)
S1-O1〜S1-O9
Chairperson:
Prof. J .N. REEVE
Prof. G. ANTRANIKIAN
Afternoon session (14:45〜17:50)
S1-O10〜S1-O18
Chairperson:
Prof. D. H. BARTLETT
Prof. R. H. DOI
Genetic Elements of Extremely Thermophilic Archaea in the Kingdom Crenarchaeota
Wolfram ZILLIG*, David PRANGISHVILI, Kenneth STEDMAN, Hans Peter ARNOLD, Anja SCHWEIER and Ingelore HOLZ
Max Planck Institut fur Biochemie, Am Klopferspitz, D 82152 Martinsried and Qunxin She, Hien Phan and Roger Garrett; Institute of Molecular Biology, Copenhagen University, Solvgade 83 H DK-1307, Copenhagen K
In view of the complete lack of knowledge of genetic elements of extremely thermophilic Crenarchaeota we have initially screened for viruses from Thermoproteales. Advantages in handling heterotrophic and aerobic Sulfolobus spp. e.g. in plating colonies and lawns and therefore in running plaque tests have led us to redirect our efforts to looking for viruses and plasmids, particularly conjugative ones, in Sulfolobus isolates from solfataric hydrothermal locations in Iceland, Japan, New Zealand and Italy. In several hundred novel strains isolated via colony plating from enrichment cultures or via direct plating of samples, some 12 novel viruses were found, all either in lysogens or in carrier states.
Seven new SSVs are similar to, but clearly different from the well known SSV1 and thus represent the novel family of spindle shaped Fuselloviridae. Fractions of particles of at least two of these, SSV2 and 3 each contain a smaller (about 7 kbp) satellite instead of the ccc SSV DNA. The satellite DNAs are not homologs of the virus DNAs, but are closely related to the multi copy plasmids pRN1 and 2 of an S. islandicus strain and pDL10 of Acidianus (formerly Desulfurolobus) ambivalens.
Two closely related stiff rod-shaped viruses, SIRV 1 and 2, represent the novel family of Rudiviridae.
Two filamentous viruses, DAFV and SIFV, also contain linear double-stranded DNA but are wrapped into a hydrophobic envelope. They represent the novel virus family Lipothrixviridae. Both in SIRV and in SIFV, the ends of the linear double stranded DNAs are covalently closed (H. Blum, personal communication).
A droplet-formed virus, SNDV from New Zealand, carries a dense beard of thin fibres on its pointed end and contains strongly modified ccc DNA 20 kbp in size. It also represents an, as yet unnamed, virus family.
In addition to these viruses, several "cryptic" and some 13 conjugative plasmids were found, the latter spreading themselves efficiently via extensive contacts between donor and recipient cells. Like the viruses, the conjugative plasmids have narrow host ranges. Three subfamilies were recognized by cross-hybridization. Members of the same subfamily are incompatible in super-conjugation. Two of these plasmids, the
