(A) Cloning of the rsmA gene of P.
fluorescens CHA0. The P. aeruginosa rsmA gene
was isolated by PCR and was used as a probe to identify the homolog in
P. fluorescens by Southern hybridization. A
1.25-kilobase genomic PstI fragment containing
rsmA of P. fluorescens was cloned. In
pME6073, rsmA on a 0.55-kilobase
PstI/PvuII fragment is expressed
from the lac promoter of the vector pME6001; in pME6083,
rsmA is deleted. The serV gene, which
encodes a serine tRNA, appears to belong to a separate transcription
unit. (B) Alignment of RsmA and CsrA amino acid
sequences. A, CsrA of E. coli (GenBank accession no.
L07596); B, RsmA of E. carotovora subsp.
carotovora 71 (L40173); C, RsmA of P.
aeruginosa (AF061757); D, RsmA of P.
fluorescens. Amino acid residues that are conserved in at least
three of the four proteins are shown in black boxes.