Identification and characterization of Pseudomonas aeruginosa PA-IIL lectin gene and protein compared to PA-IL

Abstract

Using the 33 N-terminal amino acids of the fucose/mannose binding lectin PA-IIL of Pseudomonas aeruginosa ATCC 33347 in a tblastn search of P. aeruginosa PAO1 genomic sequence in GenBank revealed a single open reading frame encoding a 114-amino acid protein (excluding initiator methionine) perfectly matching that amino acid sequence. Following its stop codon there is a GC-rich sequence having a perfect dyad symmetry promoting formation of a hairpin loop structure, potentially enabling rho-independent transcription termination. Upstream of the putative ribosomal binding site there are sequences resembling Vibrio fischeri luxI box, consistent with autoinduction of this gene. The predicted PA-IIL molecular mass, confirmed by mass spectrometry, is 11 732 Da. Its p I is 3.88. The C-terminal domain is particularly hydrophobic, implying possible embedding in the cell membrane. PA-IIL is similar to P. aeruginosa PA-IL lectin in some amino acids and potential glycosylation sites but lacks cysteine, methionine and histidine. Despite their relations in functions and regulation, their genes are widely separated (by about 867.5 kb).