20971898
not annotated - annotated - LINNAEUS only
Nucleotide parasitism by Simkania negevensis (Chlamydiae).
Intracellular bacteria live in an environment rich in most essential metabolites but need special mechanisms to access these substrates. Nucleotide transport proteins (NTTs) catalyze the import of ATP and other nucleotides from the eukaryotic host into the bacterial cell and render de novo synthesis of these compounds dispensable. The draft genome sequence of Simkania negevensis strain Z, a chlamydial organism considered a newly emerging pathogen, revealed four genes encoding putative nucleotide transport proteins (SnNTT1 to SnNTT4), all of which are transcribed during growth of S. negevensis in Acanthamoeba host cells, as confirmed by reverse transcription-PCR. Using heterologous expression in Escherichia coli, we could show that SnNTT1 functions as an ATP/ADP antiporter, SnNTT2 as a guanine nucleotide/ATP/H(+) symporter driven by the membrane potential, and SnNTT3 as a nucleotide triphosphate antiporter. In addition, SnNTT3 is able to transport dCTP, which has not been shown for a prokaryotic transport protein before. No substrate could be identified for SnNTT4. Taking these data together, S. negevensis employs a set of nucleotide transport proteins to efficiently tap its host's energy and nucleotide pools. Although similar to other chlamydiae, these transporters show distinct and unique adaptations with respect to substrate specificities and mode of transport.
Ann file
T1 Species 25 44 Simkania negevensis
N1 Reference T1 Taxonomy:83561
T2 Species 422 450 Simkania negevensis strain Z
N2 Reference T2 Taxonomy:83561
T3 Species 646 659 S. negevensis
N3 Reference T3 Taxonomy:83561
T4 Species 764 780 Escherichia coli
N4 Reference T4 Taxonomy:562
T5 Species 1169 1182 S. negevensis
N5 Reference T5 Taxonomy:83561