2.A.115 The Novobiocin Exporter (NbcE) Family The NbcE (formerly the YitT (DUF161)) family consists mostly of 6 TMS proteins, where these TMSs are frequently in a 2 2 2 arrangement. However, distant 5 and 3 TMS proteins may be members of this family. Several homologues are annotated as exporters or efflux transporters. The 3-d structure (PDB# 3HLU_A) is available for YitT of Bacillus subtilis. This protein has a DUF161-DUF161-DUF2179 domain arrangement according to CDD. Most homologues are from bacteria with a preponderance from firmicutes, but others are found in more distantly related organisms. One homologue, NbcE of Lactobacillus brevis, has been shown to be a novobiocin exporter (TC# 2.A.115.2.4). It has 195 aas and 4 or 5 TMSs (Pagliai et al. 2010).
References:
Pagliai, F.A., C.L. Gardner, S.G. Pande, and G.L. Lorca. (2010). LVIS553 transcriptional regulator specifically recognizes novobiocin as an effector molecule. J. Biol. Chem. 285: 16921-16930.
Examples:
TC#	Name	Organismal Type	Example
2.A.115.1.1	The YitT (UPF0750) efflux transporter of 280 aas and 6 pr 7 N-terminal TMSs. The 3-d structure is known (PDB# 3HLU_A).	Bacteria	*YitT of Bacillus subtilis* (P39803)**

2.A.115.1.2	The YxkD (UPF0750) membrane protein	Bacteria	*YxkD of Bacillus subtilis* (P94357)**

2.A.115.1.3	The Hypothetical Protein, HP. 6 TMSs in a 2+2+2 arrangement.	Bacteria	*HP of Rhizobium etli* (Q2KCS0)**

2.A.115.1.4	DUF161 protein of unknown function (6 TMSs in a 2+2+2 arrangement).	Bacteria	*DUF161 protein of Brucella sp.* NF 2653 (E0DTC9)**

2.A.115.1.5	Conserved uncharacterized protein of 289 aas; DUF161 + DUF2179	Proteobacteria	HP of Desulfohalobium retbaense

2.A.115.1.6	DUF2179 protein of unknown function (3 TMSs)	Bacteria	*DUF2179 protein of Mestoga prima* (E0HYB9)**

2.A.115.1.7	Uncharacterized protein of 222 aas and 3 N-terminal TMSs.	Archaea	*Uncharacterized 3 TMS protein of Methanoregula boonei* (A7I6E8)**

2.A.115.1.8	DUF2179 protein of 196 aas	Thermotogae	DUF2179 protein of Petrotoga mobilis

Examples:
TC#	Name	Organismal Type	Example
2.A.115.2.1	The 5 TMS YczE protein. May be distantly related to CirC (5TMSs; 9.B.98.1.4).	Bacteria	*YczE of Bacillus subtilis* (E0U2C9)**

2.A.115.2.10	Uncharacterized protein of 215 aas	Euryarchaea	UP of Methanocorpusculum labreanum

2.A.115.2.11	Hypothetical 6 TMS protein, HP	Bacteria	*HP of Haloplasma contractile* (F7PTN4)**

2.A.115.2.12	Uncharacterized protein of 212 aas	Firmicutes	UP of Faecalibacterium prausnitzii

2.A.115.2.13	Uncharacterized protein of 205 aas	Firmicutes	UP of Clostridium difficile

2.A.115.2.14	Fusion protein of DUF161 membrane domain of 6 TMSs with a cytidylate kinase 2 domain; 428 aas	Actinobacteria	Fusion protein of Slackia heliotrinireducens

2.A.115.2.15	Uncharacterized protein of 222 aas	*Deinococcus/Thermus*	UP of Deinococcus radiodurans

2.A.115.2.2	The 5 TMS YyaS protein	Bacteria	*YyaS of Bacillus pseudofirmus* (D3FUL0)**

2.A.115.2.3	The 5 TMS membrane protein, 5-MP	Bacteria	*5-MP of Enterococcus faecalis* (F2MS25)**

2.A.115.2.4	*Novobiocin exporter, NbcE, of 195 aas and 4 or 5 TMSs (Pagliai et al.* 2010).**	Firmicutes	Novobiocin exporter of Lactobacillus brevis

2.A.115.2.5	COG2364 homologue of 221 aas	Firmicutes	COG2364 homologue of Bacillus cereus

2.A.115.2.6	Hypothetical protein of 238 aas	Actinobacteria	HP of Kytococcus sedentarius

2.A.115.2.7	Hypotheitical protein of 224 aas	Actinobacteria	HP of Thermobifida fusca

2.A.115.2.8	Hypothetical protein of 222 aas	Spirochaetes	HP of Brachyspira hyodysenteriae

2.A.115.2.9	Uncharacterized protein of 238 aas	Firmicutes	UP of Eubacterium eligens

Examples:
TC#	Name	Organismal Type	Example
Examples:
TC#	Name	Organismal Type	Example