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3.A.1.12.5
Uptake system for glycine-betaine (high affinity) and proline (low affinity) (OpuAA-OpuABC) or BusAA-ABC of Lactococcus lactis). BusAA, the ATPase subunit, has a C-terminal tandem cystathionine β-synthase (CBS) domain which is the cytoplasmic K+ sensor for osmotic stress (osmotic strength)while the BusABC subunit has the membrane and receptor domains fused to each other (Biemans-Oldehinkel et al., 2006; Mahmood et al., 2006; Gul et al. 2012). An N-terminal amphipathic α-helix of OpuA is necessary for high activity but is not critical for biogenesis or the ionic regulation of transport (Gul et al., 2012). ATP and glycine betaine dependences of conformational changes have been examined (Tassis et al. 2020).  OpuA senses osmotic stress via changes in the internal ionic strength and is regulated by the 2nd messenger cyclic-di-AMP. The SBDs transiently interact in an ionic strength-dependent manner. The physical interactions between SBDs and cooperativity in substrate delivery are part of the transport mechanism (van den Noort et al. 2024).

Accession Number:Q9RQ06
Protein Name:BusAA
Length:407
Molecular Weight:45697.00
Species:Lactococcus lactis [1358]
Location1 / Topology2 / Orientation3: Cell membrane1 / Multi-pass membrane protein2
Substrate glycine betaine, proline

Cross database links:

Pfam: PF00005    PF00571   

Gene Ontology

GO:0016020 C:membrane
GO:0015171 F:amino acid transmembrane transporter activity
GO:0005524 F:ATP binding
GO:0016887 F:ATPase activity
GO:0006865 P:amino acid transport

References (1)

[1] “Genetic and biochemical characterization of a high-affinity betaine uptake system (BusA) in Lactococcus lactis reveals a new functional organization within bacterial ABC transporters.”  Obis D.et.al.   10515910

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FASTA formatted sequence
1:	MPVKVKIEHL TKIFGKRIKT ALTMVEQGEP KNEILKKTGA TVGVYDTNFE INEGEIFVIM 
61:	GLSGSGKSTL LRLLNRLIEP TSGKIFIDDQ DVATLNKEDL LQVRRKSMSM VFQNFGLFPH 
121:	RTILENTEYG LEVQNVPKEE RRKRAEKALD NANLLDFKDQ YPKQLSGGMQ QRVGLARALA 
181:	NDPEILLMDE AFSALDPLIR REMQDELLEL QAKFQKTIIF VSHDLNEALR IGDRIAIMKD 
241:	GKIMQIGTGE EILTNPANDY VKTFVEDVDR AKVITAENIM IPALTTNIDV DGPSVALKKM 
301:	KTEEVSSLMA VDRKRQFRGV VTSEQAIAAR KNNQSLKDVM TTDVGTVTKE MLVRDILPII 
361:	YDAPTPLAVV DDQGYLKGIL IRGIVLEALA DIPDEVEEIE KEEEKND