Viruses infecting marine picoplancton encode functional potassium ion channels

Siotto, Fenja; Martin, Corinna; Rauh, Oliver; Etten, James L. Van; Schroeder, Indra; Moroni, Anna; Thiel, Gerhard

doi:10.1016/j.virol.2014.05.002

Cited by 17 publications

(25 citation statements)

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“…We have previously reported that some viruses, which infect unicellular marine algae, also encode genes with the hallmarks of K + channels (Siotto et al, 2014). An initial functional testing of some of these proteins revealed that they have non-canonical architectures in their TM domains, but that they still form functional K + channels (Siotto et al, 2014). Here we perform a comparative examination of K + channels, which are similar in their structure but fundamentally different in their voltage dependency.…”

Section: Introductionmentioning

confidence: 95%

“…Here we further exploit the diversity of viral K + channel genes by screening viral K + channels from a marine habitat. We have previously reported that some viruses, which infect unicellular marine algae, also encode genes with the hallmarks of K + channels (Siotto et al, 2014). An initial functional testing of some of these proteins revealed that they have non-canonical architectures in their TM domains, but that they still form functional K + channels (Siotto et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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A small viral potassium ion channel with an inherent inward rectification

Eckert

Schulze

Stahl

et al. 2019

Preprint

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Some algal viruses have coding sequences for K + channels with structural and functional characteristics of pore modules of complex K + channels. Here we exploit the immense structural diversity of natural channel orthologs to discover new basic principles of structure/function correlates in K + channels. The comparative analysis of three similar K + channels with monomer sizes ≤ 86 amino acids (AA) shows that one channel (Kmpv 1 ) generates an ohmic conductance in HEK293 cells while the other two channels (Kmpv SP1 , Kmpv PL1 ) exhibit typical features of canonical Kir channels. Like Kir channels, the rectification of the viral channels is a function of the K + driving force. Reconstitution of Kmpv SP1 and Kmpv PL1 in planar lipid bilayers showed rapid channel fluctuations only at voltages negative of the K + reversal voltage. This rectification was maintained in KCl buffer with 1 mM EDTA, which excludes blocking cations as the source of rectification. This means that rectification of the viral channels must be, unlike Kir channels, an inherent property of the channel proteins. The structural basis for rectification was investigated by a chimera between rectifying and non-rectifying channels as well as point mutations, which made the rectifying channels similar to the ohmic conducting channel. The results of these experiments exclude the domain, which connects the two transmembrane helixes and which includes the pore helix and the selectivity filter, as playing a major role in rectification; inward rectification must be conferred by the transmembrane domains. The finding that a swapping of the AA, which is typical for the two inward rectifiers, with the respective AA from Kmpv 1 did not compromise rectification suggests that tertiary or quaternary structural interactions are responsible for this type of gating.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

A small viral potassium ion channel with an inherent inward rectification

Eckert

Schulze

Stahl

et al. 2019

Preprint

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“…[105][106][107][108] Their structure is that of an extremely reduced Kir channel: 2 transmembrane helices per monomer are connected by a short loop containing the consensus K C selectivity filter sequence and the characteristic pore helix. The protein does not contain any cytosolic or extracellular domains and it is fully embedded in the lipid bilayer.…”

Section: Channelmentioning

confidence: 99%

“…Each monomer is made of 2 transmembrane domains, which are connected by the pore helices. [105][106][107][108] A further advantage of these channels is that members differ only by a few amino acids, but show quite different functional properties. This guides the experimenter to those residues, which are crucial for function.…”

Section: Supplementing 2-dimensional Dwell-time Analysis By the Analymentioning

confidence: 99%

How to resolve microsecond current fluctuations in single ion channels: The power of beta distributions

Schroeder

2015

Channels

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A main ingredient for the understanding of structure/ function correlates of ion channels is the quantitative description of single-channel gating and conductance. However, a wealth of information provided from fast current fluctuations beyond the temporal resolution of the recording system is often ignored, even though it is close to the time window accessible to molecular dynamics simulations. This kind of current fluctuations provide a special technical challenge, because individual opening/closing or blocking/ unblocking events cannot be resolved, and the resulting averaging over undetected events decreases the singlechannel current. Here, I briefly summarize the history of fastcurrent fluctuation analysis and focus on the so-called "beta distributions." This tool exploits characteristics of current fluctuation-induced excess noise on the current amplitude histograms to reconstruct the true single-channel current and kinetic parameters. A guideline for the analysis and recent applications demonstrate that a construction of theoretical beta distributions by Markov Model simulations offers maximum flexibility as compared to analytical solutions.

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“…In contrast, the flexible pan-genome comprises many genes of unknown function, but also contains some metabolic genes similar to the auxiliary metabolic genes (AMGs) found in cyanophages [17]. The genomes vary in the transfer RNAs (tRNAs) [12] and K + channels [18] that are encoded. Additionally, Ostreococcus viruses possess genes of presumed cellular origin, some with homologues in their hosts.…”

Section: Introductionmentioning

confidence: 99%

Variation in the Genetic Repertoire of Viruses Infecting Micromonas pusilla Reflects Horizontal Gene Transfer and Links to Their Environmental Distribution

Finke

Winget

Chan

et al. 2017

Viruses

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Prasinophytes, a group of eukaryotic phytoplankton, has a global distribution and is infected by large double-stranded DNA viruses (prasinoviruses) in the family Phycodnaviridae. This study examines the genetic repertoire, phylogeny, and environmental distribution of phycodnaviruses infecting Micromonas pusilla, other prasinophytes and chlorophytes. Based on comparisons among the genomes of viruses infecting M. pusilla and other phycodnaviruses, as well as the genome from a host isolate of M. pusilla, viruses infecting M. pusilla (MpVs) share a limited set of core genes, but vary strongly in their flexible pan-genome that includes numerous metabolic genes, such as those associated with amino acid synthesis and sugar manipulation. Surprisingly, few of these presumably host-derived genes are shared with M. pusilla, but rather have their closest non-viral homologue in bacteria and other eukaryotes, indicating horizontal gene transfer. A comparative analysis of full-length DNA polymerase (DNApol) genes from prasinoviruses with their overall gene content, demonstrated that the phylogeny of DNApol gene fragments reflects the gene content of the viruses; hence, environmental DNApol gene sequences from prasinoviruses can be used to infer their overall genetic repertoire. Thus, the distribution of virus ecotypes across environmental samples based on DNApol sequences implies substantial underlying differences in gene content that reflect local environmental conditions. Moreover, the high diversity observed in the genetic repertoire of prasinoviruses has been driven by horizontal gene transfer throughout their evolutionary history, resulting in a broad suite of functional capabilities and a high diversity of prasinovirus ecotypes.

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Viruses infecting marine picoplancton encode functional potassium ion channels

Cited by 17 publications

References 50 publications

A small viral potassium ion channel with an inherent inward rectification

A small viral potassium ion channel with an inherent inward rectification

How to resolve microsecond current fluctuations in single ion channels: The power of beta distributions

Variation in the Genetic Repertoire of Viruses Infecting Micromonas pusilla Reflects Horizontal Gene Transfer and Links to Their Environmental Distribution

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