TABLE 1.

List of putative pilus biogenesis genes in the Nostoc punctiforme ATCC 29133 genome^a

N. punctiforme gene	No. of aa residues encoded	Annotation (Nostoc genome)	Homologous gene in P. aeruginosa/Synechocystis strain PCC 6803b	Proposed function/productc	Mutant phenotypec	References
NpR0117*	375	pilT	pilT*	Pilus retraction	Hyperpiliated, nonmotile	7, 8, 39, 40, 47, 57
NpF2507*	425	pilT	pilT*	Pilus retraction/phototaxisd	Hyperpiliated, nonmotile/negative phototaxisd	7, 8, 39, 40, 47, 57
NpR2800*	293	Prepilin peptidase gene pulO	pilD*	Prepilin peptidase	Loss of motility and Tfp	3, 7, 25, 38, 49, 50, 51, 63
NpF0676*	188	Tfp assembly protein pilE	pilA	Prepilin	Loss of motility and Tfp	6, 7, 28, 42, 47, 63
NpF0067	226	pulG pseudopilin	pilA	Prepilin	Loss of motility and Tfp	6, 7, 28, 42, 47, 63
NpF0068*	322	Hypothetical	pilA*	Prepilin	Loss of motility and Tfp	6, 7, 28, 42, 47, 63
NpF0069*	232	Tfp assembly protein FimT gene	pilA*	Prepilin	Loss of motility and Tfp	6, 7, 28, 42, 47, 63
NpF0073	185	pulG pseudopilin gene	pilA*	Prepilin	Loss of motility and Tfp	6, 7, 28, 42, 47, 63
NpR0118	668	pilB	pilB	Pilus extension	Loss of motility and Tfp	28, 36, 52, 57, 63
NpF2747	371	pilB	pilB	Pilus extension	Loss of motility and Tfp	28, 36, 52, 57, 63
NpR0116	411	GSP member pulF	pilC	Counteracts PilT-mediated pilus retraction	Loss of motility and Tfp	36, 39
NpF5005	368	pilM	PilM	Unknown	Loss of motility and Tfp	27, 63
NpF5006	255	pilN	pilN	Localization/stability of Tfp	Loss of motility and Tfp	27, 63
NpF5007	258	pilO	pilO	Localization/stability of Tfp	Loss of motility and Tfp	27, 63
NpF5008	792	pilQ	pilQ	Pore-forming secretin	Loss of motility and Tfp	26, 63

^a*, ORFs chosen for characterization in the present study.

^bNostoc pil-related genes were identified by searching the protein database derived from the genome of N. punctiforme with deduced amino acid sequences of the known P. aeruginosa and Synechocystis strain PCC 6803 pil proteins.

^cThe proposed functions and mutant phenotypes are based primarily on that established for P. aeruginosa but is also based on that for Synechocystis, unless otherwise noted.

^dPhototaxis is a proposed function/phenotype for Synechocystis only.