Recombinant Protochlamydia amoebophila Cytidylate kinase (cmk)

Introduction

Protochlamydia amoebophila is an obligate intracellular bacterium belonging to the Chlamydiales order. While related to Chlamydiaceae, which includes major human pathogens, P. amoebophila thrives as a symbiont within protozoa such as Acanthamoeba sp. . Unlike the metabolically inert elementary bodies (EBs) of other Chlamydiae, P. amoebophila EBs maintain respiratory activity and metabolize D-glucose . This metabolic activity is crucial for maintaining infectivity .

Metabolic Features of Protochlamydia amoebophila

Studies have shown that P. amoebophila EBs actively metabolize D-glucose via the pentose phosphate pathway and possess a functional tricarboxylic acid (TCA) cycle . This activity includes substrate uptake, synthesis of labeled metabolites, and the release of labeled CO2 from 13C-labeled D-glucose . The availability of D-glucose is essential for sustaining metabolic activity, as its replacement with a non-metabolizable sugar leads to a rapid decline in the number of infectious particles .

Nucleotide Transport

The genome of P. amoebophila encodes five paralogous carrier proteins belonging to the nucleotide transporter (NTT) family . These proteins facilitate the transport of nucleotides, connecting the bacteria intimately with their host cell’s metabolism . Three characterized P. amoebophila NTT isoforms—PamNTT2, PamNTT3, and PamNTT5—exhibit unique substrate specificities and transport modes . PamNTT2 is a counter-exchange transporter for all four RNA nucleotides, PamNTT3 catalyzes a unidirectional proton-coupled transport of UTP, and PamNTT5 mediates a proton-energized GTP and ATP import .

Apoptosis Induction

Protochlamydia can induce apoptosis in human immortal cell lines such as HEp-2 cells, but not in primary peripheral blood mononuclear cells (PBMCs) . This apoptosis induction requires the attachment of viable bacterial cells, but not an increase of bacterial infectious progenies within the cells . Other chlamydiae, like Parachlamydia acanthamoebae and Chlamydia trachomatis, do not induce the same phenomena, suggesting that the observed apoptosis may be specific to Protochlamydia .

Cytidylate Kinase (Cmk)

While the provided information does not explicitly detail "Recombinant Protochlamydia amoebophila Cytidylate kinase (Cmk)," cytidylate kinase is an enzyme that catalyzes the phosphorylation of cytidine monophosphate (CMP) to cytidine diphosphate (CDP), utilizing ATP as the phosphate donor. Cytidylate kinase is crucial for maintaining cellular nucleotide pools and is involved in DNA and RNA synthesis.

Relevance to Research

The study of Protochlamydia amoebophila and its enzymes like cytidylate kinase offers insights into the metabolic adaptations of intracellular bacteria and their interactions with host cells . Understanding these interactions may provide tools for novel therapeutic strategies, such as the development of drugs that target essential bacterial enzymes or exploit the apoptosis-inducing capabilities of Protochlamydia .

Tables

Table 1: Metabolic Features of Protochlamydia amoebophila Elementary Bodies (EBs)

Table 2: Characteristics of Protochlamydia amoebophila Nucleotide Transporters (NTTs)