Ss-bCNGa: a unique member of the bacterial cyclic nucleotide gated (bCNG) channel family that gates in response to mechanical tension.
Bacterial cyclic nucleotide gated (bCNG) channels are generally a nonmechanosensitive subset of the mechanosensitive channel of small conductance (MscS) superfamily. bCNG channels are composed of an MscS channel domain, a linking domain, and a cyclic nucleotide binding domain. Among bCNG channels, the channel domain of Ss-bCNGa, a bCNG channel from Synechocystis sp. PCC 6803, is most identical to Escherichia coli (Ec) MscS. This channel also exhibits limited mechanosensation in response to osmotic downshock assays, making it the only known full-length bCNG channel to respond to hypoosmotic stress. Here, we compare and contrast the ability of Ss-bCNGa to gate in response to mechanical tension with Se-bCNG, a nonmechanosensitive bCNG channel, and Ec-MscS, a prototypical mechanosensitive channel. Compared with Ec-MscS, Ss-bCNGa only exhibits limited mechanosensation, which is most likely a result of the inability of Ss-bCNGa to form the strong lipid contacts needed for significant function. Unlike Ec-MscS, Ss-bCNGa displays a mechanical response that increases with protein expression level, which may result from channel clustering driven by interchannel cation-π interactions.
Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
Hannah R
HR
Malcolm
Yoon-Young
YY
Heo
David B
DB
Caldwell
John K
JK
McConnell
Jessica F
JF
Hawkins
Ryann C
RC
Guayasamin
Donald E
DE
Elmore
Joshua A
JA
Maurer
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry; D015870:Gene Expression; D015640:Ion Channel Gating; D050356:Lipid Metabolism; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009712:Nucleotides, Cyclic / Q000378:metabolism; D009997:Osmotic Pressure; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013314:Stress, Mechanical; D046939:Synechocystis / Q000737:chemistry
D001426:Bacterial Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D009712:Nucleotides, Cyclic