TY  - JOUR
A1  - Lindt, Katharina-Astrid
A1  - Frühschulz, Stefan
A1  - Tampé, Robert
A1  - Abele, Rupert
T1  - Interdomain communication in a homodimeric ABC transporter
T2  - Journal of biological chemistry
N2  - ABC transporters are found in all organisms and almost every cellular compartment. They mediate the transport of various solutes across membranes, energized by ATP binding and hydrolysis. Dysfunctions can result in severe diseases, such as cystic fibrosis or antibiotic resistance. In type IV ABC transporters, each of the two nucleotide-binding domains is connected to a transmembrane domain by two coupling helices, which are part of cytosolic loops. Although there are many structural snapshots of different conformations, the interdomain communication is still enigmatic. Therefore, we analyzed the function of three conserved, charged residues in the intra-cytosolic loop 1 of the human homodimeric, lysosomal peptide transporter TAPL. Substitution of D278 in coupling helix 1 by alanine interrupted peptide transport by impeding ATP hydrolysis. Alanine substitution of R288 and D292, both localized next to the coupling helix 1 extending to transmembrane helix 3, reduced peptide transport but increased basal ATPase activity. Surprisingly, the ATPase activity of the R288A variant dropped in a peptide-dependent manner while ATPase activity of wildtype and D292A was unaffected. Interestingly, R288A and D292A mutants did not differentiate between ATP and GTP in respect of hydrolysis. However, in contrast to wildtype TAPL, only ATP energized peptide transport. In sum, D278 seems to be involved in bidirectional interdomain communication mediated by network of polar interactions while the two residues in the cytosolic extension of TMH3 are involved in regulation of ATP hydrolysis, most likely by stabilization of the outward facing conformation.
KW  - ABC transporters
KW  - TAPL
KW  - interdomain signal transmission
KW  - interaction network
KW  - allosteric coupling
Y1  - 2024
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/85851
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-858511
SN  - 0021-9258
VL  - 300
IS  - 7, 107440
PB  - ASBMB Publications
CY  - Bethesda, Md.
ER  -