Background: Phosphoenolpyruvate carboxykinase (Pck) catalyzes the interconversion of phosphoenolpyruvate and oxaloacetate but typically prefers gluconeogenic formation of phosphoenolpyruvate. Results: Interactions of Mycobacterium tuberculosis (MTb) Pck with thioredoxin and reducing environments favor the anaplerotic oxaloacetate synthesis. Conclusion: A mechanism explaining the regulation of Pck functions is proposed. Significance: Regulation of Pck is important for the MTb non-replicative state associated with latent tuberculosis infection.

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Adenosine kinase (ADK) from Mycobacterium tuberculosis (Mtb) was selected as a target for design of antimycobacterial nucleosides. Screening of 7-(het)aryl-7-deazaadenine ribonucleosides with Mtb and human (h) ADKs and testing with wild-type and drug-resistant Mtb strains identified specific inhibitors of Mtb ADK with micromolar antimycobacterial activity and low cytotoxicity. X-ray structures of complexes of Mtb and hADKs with 7-ethynyl-7-deazaadenosine showed differences in inhibitor interactions in the adenosine binding sites. 1D (1)H STD NMR experiments revealed that these inhibitors are readily accommodated into the ATP and adenosine binding sites of Mtb ADK, whereas they bind preferentially into the adenosine site of hADK. Occupation of the Mtb ADK ATP site with inhibitors and formation of catalytically less competent semiopen conformation of MtbADK after inhibitor binding in the adenosine site explain the lack of phosphorylation of 7-substituted-7-deazaadenosines. Semiempirical quantum mechanical analysis confirmed different affinity of nucleosides for the Mtb ADK adenosine and ATP sites.

Several types of isopolar modified oligothymidylates and oligoadenylates (15 mers) with the phosphonate -O-P-CH2-O- internucleotide linkage were prepared. The modified oligonucleotides were subjected to the study of their hybridization properties, resistance against nucleases, and the ability to elicit RNase H activity.

4'-Alkoxy-oligothymidylates were prepared as model compounds to study the influence of a C4'-alkoxy group on hybridisation. The phosphodiester homooligomers (15 units long) containing either a 4'-methoxy or 4'-(2-methoxyethoxy) group were found to display increased hybridisation with both dA(15) and rA(15) complementary counterparts compared to the natural oligothymidylate. In addition, we found their hybridisation behaviour to be similar to that of the regioisomeric 2'-O-methyl-oligothymidylate. The formed complexes (duplexes and triplexes) were studied using UV spectroscopy and polyacrylamide gel electrophoresis (PAGE). Structural background of the hybridization behaviour was examined using NMR and MDS. The favourable hybridisation properties of the 4'-alkoxyoligothymidylates indicated that 4'-alkoxy modified nucleotides are promising compounds for the assembly of chimeric oligonucleotides with tunable properties.