Prochlorothrix hollandica PCC 9006: genomic properties of an axenic representative of the chlorophyll a/b-containing oxyphotobacteria.
Prochlorothrix hollandica is an oxygenic photosynthetic prokaryote that differs from the cyanobacteria in having chlorophyll a/b-protein complexes instead of phycobilisomes as major light-harvesting antennae. We report the isolation and culturing of an axenic strain of P. hollandica, available from the Pasteur Culture Collection of Cyanobacteria as strain PCC 9006. The strain has a mean DNA base composition of 51.6 +/- 0.1 mol% G+C and a genomic complexity of 3.37 +/- 0.17 x 10(9) daltons (5,505 kb). A reiterated DNA sequence represents approximately 4.4% of the genome. Restriction enzyme isoschizomers with different sensitivities to base methylation were used to demonstrate that most A residues in the sequence GATC are methylated in P. hollandica DNA and that this methylation increases with culture age. Furthermore, some C residues are methylated, although the specificity of the C methylation system does not match that of well-characterized C methylases. Nucleotide analysis showed that up to approximately 3.5% of both dA and dC residues are methylated in P. hollandica DNA.
Schyns
G
G
Unité de Physiologie microbienne (CNRS URA 1129), Institut Pasteur, Paris.
Rippka
R
R
Namane
A
A
Campbell
D
D
Herdman
M
M
Houmard
J
J
D020029:Base Pairing; D002734:Chlorophyll; D000077194:Chlorophyll A; D019175:DNA Methylation; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D045524:Phycobilisomes; D019692:Prochlorothrix / Q000235:genetics* / Q000254:growth & development; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D013997:Time Factors
D004269:DNA, Bacterial; D045524:Phycobilisomes; D002734:Chlorophyll; C037184:chlorophyll b; D000077194:Chlorophyll A