9.B.67 The O-antigen Polymerase (OAP) Family The O-antigen polymerase (ligase) family (COG3307) consists of proteins of this function. It is probable that O-antigen polymerases facilitate export of intermediates of LPS biosynthesis. Several of the proteins listed in this table are distantly related to each other, but homology has been established (DE Chen and MH Saier, unpublished results). This family may be distantly related to 9.B.128, also designated as an O-antigen polymerase family. A homologue designated IctB or ORF467 in Synechococcus sp. strain PCC7942 was reprted to be a Na⁺:HCO₃^- symporter, but this conclusion may have been in error. The probable transport reaction proposed for OAP family members is: O-antigen precursor (in) → O-antigen precursor (out).
This family belongs to the O-Antigen Polymerase (OAPol) Superfamily.
References:
Bonfil, D.J., M. Ronen-Tarazi, D. Sültemeyer, J. Lieman-Hurwitz, D. Schatz, and A. Kaplan. (1998). A putative HCO₃^- transporter in the cyanobacterium Synechococcus sp. strain PCC7942. FEBS Lett. 430: 236-240.
Pan, Y., X. Ruan, M.A. Valvano, and L. Konermann. (2012). Validation of membrane protein topology models by oxidative labeling and mass spectrometry. J Am Soc Mass Spectrom 23: 889-898.
Schild, S., A.K. Lamprecht, and J. Reidl. (2005). Molecular and functional characterization of O antigen transfer in Vibrio cholerae. J. Biol. Chem. 280: 25936-25947.
Tyrrell, P.N., R.A. Kandasamy, C.M. Crotty, and G.S. Espie. (1996). Ethoxyzolamide differentially inhibits CO₂ uptake and Na⁺-independent and Na⁺-dependent HCO₃^- uptake in the cyanobacterium Synechococcus sp. UTEX 625. Plant Physiol. 112: 79-88.
Examples:
TC#	Name	Organismal Type	Example
9.B.67.1.1	The putative HCO₃^-:Na⁺ symporter, IctB	Cyanobacteria	*IctB of Synechococcus* sp. strain PCC7942 (AAB08477)**

9.B.67.1.2	Uncharacterized protein of the O-antigen polymerase (OAP) family; of 397 aas and 11 or 12 TMSs.	Firmicutes	Uncharacterized protein of Streptococcus pneumoniae

9.B.67.1.3	Uncharacterized protein	Firmicutes	UP of Pelotomaculum thermopropionicum

9.B.67.1.4	Uncharacterized protein of 634 aas and 13 or 14 TMSs.	Lentisphaerae	UP of Lentisphaera araneosa

9.B.67.1.5	Uncharacterized protein of 450 aas and 10 TMSs.		UP of Candidatus Beckwithbacteria bacterium

Examples:
TC#	Name	Organismal Type	Example
9.B.67.2.1	O-antigen polymerase, Rfc	Bacteria	*Rfc of E. coli* (P37748)**

9.B.67.2.2	Oligosaccharide repeat unit polymerase, Wzy	Firmicutes	Wzy of Streptococcus pneumoniae

9.B.67.2.3	Uncharacterized protein, MutG of 398 aas	Proteobacteria	MutG of Neisseria wadsworthii

9.B.67.2.4	Uncharacterized protein of 427 aas	Deinococcus/Thermus	UP of Deinococcus deserti

Examples:
TC#	Name	Organismal Type	Example
9.B.67.3.1	O-antigen polymerase, Wzy	Bacteria	*Wzy of E. coli* (AAV85961)**

9.B.67.3.2	Hypothetical protein (H.P.) (460 aas; 14 TMSs)	Bacteria	*H.P. of Bacteroides uniformis* (A7V2W2)**

9.B.67.3.3	Uncharacterized protein of 441 aas	Bacteroidetes	UP of Bacteroides fluxus

9.B.67.3.4	Uncharacterized protein of 432 aas	Proteobacteria	UP of Acinetobacter haemolyticus

9.B.67.3.5	Uncharacterized protein of 454 aas	Bacteroidetes	UP OF Bacteroides oleiciplenus

9.B.67.3.6	Uncharacterized protein of 369 aas	Thermatogae	UP of Fervidobacterium pennivorans

9.B.67.3.7	O-antigen lipopolysaccharide polymerase of the Wzy family, of 447 aas and 14 TMSs.		Wzy homologue of E. coli

9.B.67.3.8	Oligosaccharide repeat unit polymerase of 449 aas and 11 or 12 TMSs. This protein shows significant sequence similarity with 9.A.29.2.1.		Polymerase of Photobacterium sanctipauli

Examples:
TC#	Name	Organismal Type	Example
9.B.67.4.1	O-antigen polymerase, WaaL	Bacteria	*WaaL of Vibrio cholerae* (AAL70926)**

9.B.67.4.2	Putative O-antigen ligase of 442 aas and 9 - 10 TMSs	Spirochaeta	O-antigen ligase of Leptospira biflexa

9.B.67.4.3	Putative O-antigen ligase, WaaL, of 419 aas and 11 TMSs.		WaaL of Bdellovibrio bacteriovorus

9.B.67.4.4	Uncharacterized O-antigen polymerase homologue of 528 aas and 12 TMSs.		UP of Candidatus Saccharibacteria bacterium

9.B.67.4.5	Uncharacterized O-antigen polymerase homologue of 435 aas and 12 TMSs		UP of Candidatus saccharibacteria bacterium

Examples:
TC#	Name	Organismal Type	Example
9.B.67.5.1	*O-antigen polymerase, RfaL (WaaL). A 12 TMS topology has been confirmed (Pan et al., 2012).*	Bacteria	*RfaL of E. coli* (AAB18599)**

Examples:
TC#	Name	Organismal Type	Example
9.B.67.6.1	Uncharacterized protein of 471 aas and 11 putative TMSs.	Bacteroidetes	UP of Porphyromonas gingivalis

9.B.67.6.2	WzyC O-antigen ligase family member of 395 aas	Bacteroidetes	WzyC homologue of Microscilla marina

9.B.67.6.3	Uncaracterized protein of 395 aas	Proteobacteria	UP of Pseudomonas putida (Arthrobacter siderocapsulatus)

9.B.67.6.4	Uncharacterized protein of 406 aas	Bacteroidetes	UP of Cellulophaga lytica

9.B.67.6.5	Uncharacterized protein of 454 aas	Bacteroidetes	UP of Gillisia limnaea

9.B.67.6.6	O-antigen polymerase of 398 aas	Chlorobi	UP of Chlorobium phaeobacteroides

9.B.67.6.7	Uncharacterized protein of 445 aas	Bacteroidetes	UP of Fulvivirga imtechensis

9.B.67.6.8	O-antigen polymerase of 426 aas and 10 TMSs.		O-antigen polymerase of Nitrobacter winogradskyi

9.B.67.6.9	O-antigen ligase (polymerase) of 747 aas and 13 TMSs. Has an N-terminal domain belonging to the PgIL_A superfamily and the C-terminal Trp repeat domain called YfgC.		Polysaccharide ligase of Candidatus Wolfebacteria bacterium

Examples:
TC#	Name	Organismal Type	Example
9.B.67.7.1	Uncharacterized protein of 444 aas and 10 or 11 TMSs.	Actinobacteria	UP of Actinomyces johnsonii

9.B.67.7.2	Uncharacterized protein of 400 aas and 10 putative TMSs.	Actinobacteria	UP of Mycobacterium smegmatis

9.B.67.7.3	O-antigen polymerase of 405 aas and 9 or 10 TMSs.	Proteobacteria	Polymerase of Xanthomonas campestris

9.B.67.7.4	Uncharacterized protein of 471 aas and 11 TMSs.	Proteobacteria	UP of Methylococcus capsulatus

Examples:
TC#	Name	Organismal Type	Example
9.B.67.8.1	Uncharacterized protein of 446 aas and 10 TMSs in an apparent 4 + 4 + 2 arrangement.		UP of Bifidobacterium catenulatum

9.B.67.8.2	O-antigen ligase of 478 aas and 10 TMSs in an 8 + 2 arrangement.		*O-antigen ligase of Paenibacillus* sp. NFR01**

9.B.67.8.3	Uncharacterized protein of 419 aas and 10 TMSs		UP of Marinitoga piezophila

9.B.67.8.4	Casular polysaccharide biosynthesis protein, CpsH, of 365 aas and 9 or 10 TMSs.		CphH of Streptococcus agalactiae