A novel TctA citrate transporter from an activated sludge metagenome: structural and mechanistic predictions for the TTT family.
We isolated a putative citrate transporter of the tripartite tricarboxylate transporter (TTT) class from a metagenomic library of activated sludge from a sewage treatment plant. The transporter, dubbed TctA_ar, shares ∼50% sequence identity with TctA of Comamonas testosteroni (TctA_ct) and other β-Proteobacteria, and contains two 20-amino acid repeat signature sequences, considered a hallmark of this particular transporter class. The structures for both TctA_ar and TctA_ct were modeled with I-TASSER and two possible structures for this transporter family were proposed. Docking assays with citrate resulted in the corresponding sets of proposed critical residues for function. These models suggest functions for the 20-amino acid repeats in the context of the two different architectures. This constitutes the first attempt at structure modeling of the TTT family, to the best of our knowledge, and could aid functional understanding of this little-studied family.
Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, 62209, Morelos, México.
Ramón Alberto
RA
Batista-García
Ayixon
A
Sánchez-Reyes
César
C
Millán-Pacheco
Víctor Manuel
VM
González-Zuñiga
Soledad
S
Juárez
Jorge Luis
JL
Folch-Mallol
Nina
N
Pastor
D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure*; D019343:Citric Acid / Q000737:chemistry; D020604:Comamonas testosteroni / Q000201:enzymology* / Q000235:genetics; D015723:Gene Library; D054892:Metagenome / Q000235:genetics; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics*; D016415:Sequence Alignment; D012722:Sewage / Q000382:microbiology
D002352:Carrier Proteins; D012722:Sewage; C020723:citrate-binding transport protein; D019343:Citric Acid
TctA; citrate; docking; gene phylogeny; metagenomic; molecular modeling