W. Chungjatupornchai et al., Isolation and characterization of Synechococcus PCC7942 promoters: tRNA(pro) gene functions as a promoter, CURR MICROB, 38(4), 1999, pp. 210-216
Promoter-active fragments of Synechococcus PCC7942 were isolated by transcr
iptional gene fusion to the promoterless beta-glucuronidase (GUS) gene of E
. coli, which was used as a reporter gene. Several of the isolated promoter
-active fragments expressed GUS activity in Synechococcus comparable to tha
t of the lambda P-R promoter. Only 10% of the isolated promoter-active frag
ments also functioned in E, coli. The transcription initiation sites of the
two promoter-active fragments, D13 and E3, were identified. The major tran
scription initiation sites of D13 and E3 in Synechococcus were located with
in the nucleotides TTTG and TTG respectively, which were identical to those
corresponding to E. coli. The inferred -10 and -35 regions of D13 were TAA
ACT and TTGTAG respectively, which conformed to the E. coli sigma(70) promo
ter. Immediately upstream of the E3 transcription initiation sites was the
tRNA(pro) (GGG) gene, which contained two regions exhibiting strong homolog
y to the major promoter elements in eukaryotic tRNA genes, but did not cont
ain the E. coli promoter element. Thus, the tRNA(pro) gene can act as a pro
moter.