Whole cell affinity for 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) in the marine bacterium Candidatus Pelagibacter st. HTCC7211 explains marine dissolved HMP concentrations.

Autor: Brennan E; Department of Microbiology, Oregon State University, Corvallis, Oregon, USA., Noell S; Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato, University of Waikato, Hamilton, New Zealand., Davis EW 2nd; Center for Quantitative Life Sciences, Oregon State University, Corvallis, Oregon, USA., Giovannoni SJ; Department of Microbiology, Oregon State University, Corvallis, Oregon, USA., Suffridge CP; Department of Microbiology, Oregon State University, Corvallis, Oregon, USA.
Jazyk: angličtina
Zdroj: Environmental microbiology reports [Environ Microbiol Rep] 2024 Oct; Vol. 16 (5), pp. e70023.
DOI: 10.1111/1758-2229.70023
Abstrakt: Vitamin B1 is a universally required coenzyme in carbon metabolism. However, most marine microorganisms lack the complete biosynthetic pathway for this compound and must acquire thiamin, or precursor molecules, from the dissolved pool. The most common version of Vitamin B1 auxotrophy is for thiamin's pyrimidine precursor moiety, 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP). Frequent HMP auxotrophy in plankton and vanishingly low dissolved concentrations (approximately 0.1-50 pM) suggest that high-affinity HMP uptake systems are responsible for maintaining low ambient HMP concentrations. We used tritium-labelled HMP to investigate HMP uptake mechanisms and kinetics in cell cultures of Candidatus Pelagibacter st. HTCC7211, a representative of the globally distributed and highly abundant SAR11 clade. A single protein, the sodium solute symporter ThiV, which is conserved across SAR11 genomes, is the likely candidate for HMP transport. Experimental evidence indicated transport specificity for HMP and mechanistically complex, high-affinity HMP uptake kinetics. Km values ranged from 9.5 pM to 1.2 nM and were dramatically lower when cells were supplied with a carbon source. These results suggest that HMP uptake in HTCC7211 is subject to complex regulation and point to a strategy for high-affinity uptake of this essential growth factor that can explain natural HMP levels in seawater.
(© 2024 The Author(s). Environmental Microbiology Reports published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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