English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Cell preparations of Acholeplasma jlorum LIT, Acholeplasma axanthum S743T, Acholeplasma granularum BTS-39T, Spiroplasma jloricola 23-6T, Mycoplasma gallisepticum S6, and Mycoplasma arginini G230T were examined for 13 cytoplasmic enzyme activities involved in the salvage and interconversion of nucleobases, nucleosides, and 5'-mononucleotides. The unique pyrophosphate-dependent nucleoside kinase activity known only in Acholeplasma laidlawii B-PG9 was found in A. axanthum and A. granularum. All the organisms could be divided into three groups based upon their patterns of purine salvage and interconversion activities. All the tested organisms, A. laidlawii, and apparently Mycoplasma mycoides subsp. mycoides lack the ability to synthesize guanylates from other purine mononucleotides, indicating that these members of the class Mollicutes can only salvage guanylates. The plant epiphytes A. florum and S. jloricola had an identical purine enzyme pattern which was different from those of all other members of the Mollicutes studied. Mollicutes (mycoplasmas) is a class of procaryotes char- acterized by lack of a cell wall, complex nutritional require- ments, and small genome of generally low guanine-plus- cytosine ratio. Nutritional studies on representatives from each of the three families within the class demonstrate the absolute requirement for nucleobases or nucleosides for growth (3, 5, 8, 11, 17-21, 23). The nutritional requirement for purine precursors suggests the lack of a functional pathway for the de novo synthesis of purines and the dependence on salvage and interconversion enzymes for the biosynthesis of purine nucleotides (11, 24). Hamet et al. (6) examined purine salvage but not nucleotide interconversion activity in a number of Mycoplasma species. Only in Mycoplasma mycoides subsp. mycoides (11, 12), a species not generally available for study in the United States, and Acholeplasma laidlawii B-PG9 (24) have the pathways in- volved in purine salvage and interconversion been com- pletely described. Here we describe our examination of the class Mollicutes for the unique pyrophosphate (PPJ-dependent nucleoside kinase activity which is only known in A. laidlawii B-PG9 (24). When first reported, we speculated that the PPi- dependent enzyme activity might prove useful in the study of the phylogenetic relationships of the Mollicutes. We now have studied six other representative Mollicutes for this PPi-dependent activity and for 12 other cytoplasmic enzyme activities involved in the salvage and interconversion of purine bases, ribonucleosides, and 5'-monophosphates.

Distinctions in Mollicutes Purine Metabolism: Pyrophosphate-Dependent Nucleoside Kinase and Dependence on Guanylate Salvage