PnuT uses a facilitated diffusion mechanism for thiamine uptake

Jaehme, Michael; Singh, Rajkumar; Garaeva, A.A.; Duurkens, Ria H.; Slotboom, Dirk Jan

doi:10.1085/jgp.201711850

Cited by 11 publications

(12 citation statements)

References 30 publications

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“…Therefore, we speculated that the pnuC motif might represent the conserved aptamer domain of a novel riboswitch class that senses and responds to a molecule in the NAD + biosynthetic pathway. However, various homologs of PnuC proteins have been proven to transport other metabolites such as thiamin (PnuT) (Jaehme et al 2018) and riboflavin (PnuX) (Vogl et al 2007), or have been proposed to transport deoxyribonucleosides (PnuN) (Rodionov and Gelfand 2005). The existence of these other proteins left open the possibility that the pnuC genes associated with this novel RNA motif were misannotated.…”

Section: Resultsmentioning

confidence: 99%

“…Values were plotted relative to the logarithm of the molar concentration of ligand, wherein half-maximal binding represents the KD. (Herbert et al 2003), a PnuT thiamin transporter (Jaehme et al 2018), a PnuX riboflavin transporter from Corynebacterium glutamicum (Vogl et al 2007), and a PnuN protein from Lactobacillus acidophilus predicted to transport a deoxynucleoside (Rodionov and Gelfand 2005).…”

Section: In-line Probing Analysesmentioning

confidence: 99%

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A second riboswitch class for the enzyme cofactor NAD⁺

Panchapakesan

Corey

Malkowski

et al. 2020

RNA

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A bacterial noncoding RNA motif almost exclusively associated with pnuC genes was uncovered using comparative sequence analysis. Some PnuC proteins are known to transport nicotinamide riboside (NR), which is a component of the ubiquitous and abundant enzyme cofactor nicotinamide adenine dinucleotide (NAD +). Thus, we speculated that the newly found 'pnuC motif' RNAs might function as aptamers for a novel class of NAD +sensing riboswitches. RNA constructs that encompass the conserved nucleotides and secondary structure features that define the motif indeed selectively bind NAD + , nicotinamide mononucleotide (NMN), and NR. Mutations that disrupt strictly conserved nucleotides of the aptamer also disrupt ligand binding. These bioinformatic and biochemical findings indicate that pnuC motif RNAs are likely members of a second riboswitch class that regulates gene expression in response to NAD + binding.

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Section: Resultsmentioning

confidence: 99%

Section: In-line Probing Analysesmentioning

confidence: 99%

A second riboswitch class for the enzyme cofactor NAD⁺

Panchapakesan

Corey

Malkowski

et al. 2020

RNA

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“…In contrast to the dissolved fraction where B 1 was the most abundant chemical form, within the particulate, B 1 and TMP are present in relatively equal abundances (IQR 47–59% and 34–43% of particulate tB 1 , respectively), and TPP was a minor contributor (IQR 4–12%) to the particulate tB 1 pool. Recently, it has been demonstrated that PnuT‐type transporters can allow passive diffusion of B 1 but not TMP or TPP across cellular membranes (Jaehme et al, ). Therefore, the observed enrichment of particulate B 1 could be the result of passive, diffusion‐based assimilation from the dissolved pool.…”

Section: Resultsmentioning

confidence: 99%

B Vitamins and Their Congeners as Potential Drivers of Microbial Community Composition in an Oligotrophic Marine Ecosystem

et al. 2018

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Determining the factors that influence marine microbial growth and community structure are critical for the understanding of global carbon cycling. Since the early twentieth century, it has been known that B vitamins play an important role in phytoplankton community dynamics. Limited oceanic dissolved B vitamin distributions indicate that these important coenzymes are present at picomolar levels, which could be too low to support maximal phytoplankton growth, and vast regions of the ocean exist where they are undetectable. Despite their importance, particulate B vitamin concentrations of field microbial populations are unknown. Here we report B vitamin concentrations measured in both the particulate and dissolved fractions, including multiple biochemically relevant B vitamin congeners. We establish their spatial distributions spanning distinct biogeographic and oceanographic regimes in the Mediterranean Sea and the Eastern Atlantic Ocean and show that all congeners are present both dissolved in seawater and in suspended particles. We observe that B vitamins cooccur in patches defined by regional biogeographic and oceanographic features. Additionally, distinct patterns of congener relative abundance in the dissolved and particulate pools provide insight to biological and chemical cycling of these compounds between and within the dissolved and particulate pools. Finally, linear model results demonstrate that model fits of microbial assemblages are strongest when they include both inorganic nutrients and dissolved B vitamin concentrations. We believe that these findings represent an advance in our understanding of B vitamin oceanographic distributions and point to interesting hypotheses of their influence on marine microbial ecology.

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“…In addition to GLUT1, other facilitated diffusion systems have been characterized in JGP , including those for uridine (Cabantchik and Ginsburg, 1977), urea, and ethylene glycol (Mayrand and Levitt, 1983). Very recently, Jaehme et al (2018) demonstrated that facilitated diffusion is the mechanism of thiamine transport through PnuT, a member of the bacterial pyridine nucleotide uptake family; this mechanism is completely different from that of other bacterial thiamine transporters.…”

Section: Simple Carriers or Uniportersmentioning

confidence: 99%

Carriers, exchangers, and cotransporters in the first 100 years of the Journal of General Physiology

Jennings

2018

Journal of General Physiology

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Transporters, pumps, and channels are proteins that catalyze the movement of solutes across membranes. The single-solute carriers, coupled exchangers, and coupled cotransporters that are collectively known as transporters are distinct from conductive ion channels, water channels, and ATP-hydrolyzing pumps. The main conceptual framework for studying transporter mechanisms is the alternating access model, which comprises substrate binding and release events on each side of the permeability barrier and translocation events involving conformational changes between inward-facing and outward-facing conformational states. In 1948, the began to publish work that focused on the erythrocyte glucose transporter-the first transporter to be characterized kinetically-followed by articles on the rates, stoichiometries, asymmetries, voltage dependences, and regulation of coupled exchangers and cotransporters beginning in the 1960s. After the dawn of cDNA cloning and sequencing in the 1980s, heterologous expression systems and site-directed mutagenesis allowed identification of the functional roles of specific amino acid residues. In the past two decades, structures of transport proteins have made it possible to propose specific models for transporter function at the molecular level. Here, we review the contribution of articles to our current understanding of solute transporter mechanisms. Whether the topic has been kinetics, energetics, regulation, mutagenesis, or structure-based modeling, a common feature of these articles has been a quantitative, mechanistic approach, leading to lasting insights into the functions of transporters.

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PnuT uses a facilitated diffusion mechanism for thiamine uptake

Cited by 11 publications

References 30 publications

A second riboswitch class for the enzyme cofactor NAD⁺

A second riboswitch class for the enzyme cofactor NAD⁺

B Vitamins and Their Congeners as Potential Drivers of Microbial Community Composition in an Oligotrophic Marine Ecosystem

Carriers, exchangers, and cotransporters in the first 100 years of the Journal of General Physiology

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PnuT uses a facilitated diffusion mechanism for thiamine uptake

Cited by 11 publications

References 30 publications

A second riboswitch class for the enzyme cofactor NAD+

A second riboswitch class for the enzyme cofactor NAD+

B Vitamins and Their Congeners as Potential Drivers of Microbial Community Composition in an Oligotrophic Marine Ecosystem

Carriers, exchangers, and cotransporters in the first 100 years of the Journal of General Physiology

Contact Info

Product

Resources

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A second riboswitch class for the enzyme cofactor NAD⁺

A second riboswitch class for the enzyme cofactor NAD⁺