scholarly journals Positively charged residues at the channel mouth boost single-file water flow

2018 ◽  
Vol 209 ◽  
pp. 55-65 ◽  
Author(s):  
Andreas Horner ◽  
Christine Siligan ◽  
Alex Cornean ◽  
Peter Pohl
Keyword(s):  
Water Flow ◽  
Channel Entrance ◽  
Single File ◽  
Charged Residues ◽  
Positively Charged

Positively charged residues in the vicinity of the channel entrance or exit accelerate single-file water flow.

scholarly journals Charged Residues at the Pore Mouth Affect Single-File Water Flow

2019 ◽  
Vol 116 (3) ◽  
pp. 241a
Author(s):  
Andreas Horner ◽  
Christof Hannesschläger ◽  
Florian Zocher ◽  
Pohl Peter
Keyword(s):  
Water Flow ◽  
Single File ◽  
Pore Mouth ◽  
Charged Residues

scholarly journals Clusters of Charged Residues at the C Terminus of MotA and N Terminus of MotB Are Important for Function of the Escherichia coli Flagellar Motor

2008 ◽  
Vol 190 (15) ◽  
pp. 5517-5521 ◽  
Author(s):  
Edan R. Hosking ◽  
Michael D. Manson
Keyword(s):  
Escherichia Coli ◽  
Flagellar Motor ◽  
Protein Levels ◽  
Partner Protein ◽  
C Terminus ◽  
N Terminus ◽  
Charged Residues ◽  
Positively Charged ◽  
Terminal Cluster

ABSTRACT MotA contains a conserved C-terminal cluster of negatively charged residues, and MotB contains a conserved N-terminal cluster of positively charged residues. Charge-altering mutations affecting these residues impair motility but do not diminish Mot protein levels. The motility defects are reversed by second-site mutations targeting the same or partner protein.

scholarly journals Membrane Topogenesis of a Type I Signal-Anchor Protein, Mouse Synaptotagmin Ii, on the Endoplasmic Reticulum

2000 ◽  
Vol 150 (4) ◽  
pp. 719-730 ◽  
Author(s):  
Yuichiro Kida ◽  
Masao Sakaguchi ◽  
Mitsunori Fukuda ◽  
Katsuhiko Mikoshiba ◽  
Katsuyoshi Mihara
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Membrane ◽  
Type I ◽  
Hydrophobic Region ◽  
Anchor Protein ◽  
Nascent Polypeptide ◽  
Charged Residues ◽  
Er Targeting ◽  
Signal Anchor ◽  
Positively Charged

Synaptotagmin II is a type I signal-anchor protein, in which the NH2-terminal domain of 60 residues (N-domain) is located within the lumenal space of the membrane and the following hydrophobic region (H-region) shows transmembrane topology. We explored the early steps of cotranslational integration of this molecule on the endoplasmic reticulum membrane and demonstrated the following: (a) The translocation of the N-domain occurs immediately after the H-region and the successive positively charged residues emerge from the ribosome. (b) Positively charged residues that follow the H-region are essential for maintaining the correct topology. (c) It is possible to dissect the lengths of the nascent polypeptide chains which are required for ER targeting of the ribosome and for translocation of the N-domain, thereby demonstrating that different nascent polypeptide chain lengths are required for membrane targeting and N-domain translocation. (d) The H-region is sufficiently long for membrane integration. (e) Proline residues preceding H-region are critical for N-domain translocation, but not for ER targeting. The proline can be replaced with amino acid with low helical propensity.

scholarly journals Hect E3 ubiquitin ligase Tom1 controls Dia2 degradation during the cell cycle

2012 ◽  
Vol 23 (21) ◽  
pp. 4203-4211 ◽  
Author(s):  
Dong-Hwan Kim ◽  
Deanna M. Koepp
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
S Phase ◽  
Temperature Sensitive ◽  
Dependent Manner ◽  
Charged Residues ◽  
Phase Progression ◽  
Positively Charged

The ubiquitin proteasome system plays a pivotal role in controlling the cell cycle. The budding yeast F-box protein Dia2 is required for genomic stability and is targeted for ubiquitin-dependent degradation in a cell cycle–dependent manner, but the identity of the ubiquitination pathway is unknown. We demonstrate that the Hect domain E3 ubiquitin ligase Tom1 is required for Dia2 protein degradation. Deletion of DIA2 partially suppresses the temperature-sensitive phenotype of tom1 mutants. Tom1 is required for Dia2 ubiquitination and degradation during G1 and G2/M phases of the cell cycle, whereas the Dia2 protein is stabilized during S phase. We find that Tom1 binding to Dia2 is enhanced in G1 and reduced in S phase, suggesting a mechanism for this proteolytic switch. Tom1 recognizes specific, positively charged residues in a Dia2 degradation/NLS domain. Loss of these residues blocks Tom1-mediated turnover of Dia2 and causes a delay in G1–to–S phase progression. Deletion of DIA2 rescues a delay in the G1–to–S phase transition in the tom1Δ mutant. Together our results suggest that Tom1 targets Dia2 for degradation during the cell cycle by recognizing positively charged residues in the Dia2 degradation/NLS domain and that Dia2 protein degradation contributes to G1–to–S phase progression.

Role of S4 positively charged residues in the regulation of Kv4.3 inactivation and recovery

2007 ◽  
Vol 293 (3) ◽  
pp. C906-C914 ◽  
Author(s):  
Matthew R. Skerritt ◽  
Donald L. Campbell
Keyword(s):  
Positive Charge ◽  
Voltage Sensitivity ◽  
Shaker Channels ◽  
Recovery From Inactivation ◽  
Kv4 Channels ◽  
Charged Residues ◽  
Arginine Residues ◽  
Voltage Sensing Domain ◽  
Positively Charged

The molecular and biophysical mechanisms by which voltage-sensitive K+ (Kv)4 channels inactivate and recover from inactivation are presently unresolved. There is a general consensus, however, that Shaker-like N- and P/C-type mechanisms are likely not involved. Kv4 channels also display prominent inactivation from preactivated closed states [closed-state inactivation (CSI)], a process that appears to be absent in Shaker channels. As in Shaker channels, voltage sensitivity in Kv4 channels is thought to be conferred by positively charged residues localized to the fourth transmembrane segment (S4) of the voltage-sensing domain. To investigate the role of S4 positive charge in Kv4.3 gating transitions, we analyzed the effects of charge elimination at each positively charged arginine (R) residue by mutation to the uncharged residue alanine (A). We first demonstrated that R290A, R293A, R296A, and R302A mutants each alter basic activation characteristics consistent with positive charge removal. We then found strong evidence that recovery from inactivation is coupled to deactivation, showed that the precise location of the arginine residues within S4 plays an important role in the degree of development of CSI and recovery from CSI, and demonstrated that the development of CSI can be sequentially uncoupled from activation by R296A, specifically. Taken together, these results extend our current understanding of Kv4.3 gating transitions.

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