Mutations in chloroplast 23S ribosomal RNA
Erythromycin resistance is conferred by mutations in the peptidyl transferase region of the 23S rRNA molecule. Although the mutations lie very close to one another in the secondary structure of the RNA, they fall into two distinct allelic groups, separated by the 888 bp intron in the rrnL gene.
5' to the intron:
Allele: er-u-37
(G>A at position equivalent to E. coli nt2057)
Strains:
Allele: er-u-AW-17
(A>G at position equivalent to E. coli nt2058)
Strains:
Allele: clr-u-1
(Although isolated as resistant to clindamycin rather than erythromycin, this mutant has an alteration identical to that of er-u-AW-17, A>G at position equivalent to E. coli nt2058. Both strains are resistant to clindamycin, erythromycin and lincomycin.)
Strains:
CC-377 clr-u-1 (nit+) mt+
Allele: er-u-RS-1
(not sequenced, but genetic analysis indicates allelism with er-u-37)
Strains:
CC-271 er-u-RS-1 spr-u-sp-23 (nit+) mt+
3' to the intron:
Allele: er-u-1a
(C>U at position equivalent to E. coli nt2611)
Strains:
CC-64 er-u-1a mt+
CC-220 er-u-1a spr-u-1-27-3 mt+
CC-295 er-u-1a nr-u-2-1 spr-u-1-H-4 mt-
CC-303 er-u-1a nr-u-2-1 spr-u-1-H-4 sr-u-sm2 mt+
CC-322 sr-u-2-60 er-u-1a spr-u-1-H-4 mt+
CC-944 ery2b er-u-1a mt+
CC-1016 ac-u-c-2-43 er-u-1a? mt+
CC-2534 DCMU4 er-u-1a
CC-2703 er-u-1a mt+
CC-2855 DCMU4 er-u-1a mt+
CC-2856 DCMU4 er-u-1a mt+
CC-2857 DCMU4 er-u-1a mt-
CC-2861 DCMU4 er-u-1a mt-
CC-2862 DCMU4 er-u-1a mt-
CC-2863 DCMU4 er-u-1a mt-
Allele: er-u-11
(C>G at position equivalent to E. coli nt2611)
Strains:
CC-216 er-u-11 (nit+) mt+
CC-221 er-u-11 nr1 sr-u-sm2 (nit+) mt-
CC-222 er-u-11 nr1 sr-u-sm2 (nit+) mt+
CC-1411 dr-u-2 er-u-11 sr-u-sm2 mt-
CC-2467 ac-u-c-2-9 er-u-11 spr-u-1-27-3 mt+
For more information on Chlamydomonas mutants, see the Allele category in ChlamyDB.
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