Modeling of Rhodopsin R135L mutant (in)activation as causative of severe night blindness

BRANDA M. M. ; GUERIN, DIEGO M.A.; GIORGETTI, A.; CARLONI, P.

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

Rhodopsin (RHO) isthe main prototypical protein of a large family called G-protein coupledreceptors (GCPC). RHO is a membrane-bound protein found in disks of retina rodcells, can associate as dimers or bigger homo-oligomers, and its 3-D structureconsists of a 7-helix bundle that spans the membrane. A large number of RHOgenetic mutations may lead to very severe retinal dysfunction and eventually toimpaired dark adaptation (?night blindness?). Elucidating the mutations role inhindering RHO to reaching the active state is key towards understanding thesignal transduction mechanism in GPCRs. In this work we use an all atom Molecular Dynamic (MD)simulation to model the active state structure of wt bovine RHO and the mutantR135L, both of them in the dimeric form. For this analysis, the protein was embeddedinto an explicit atom solvated membrane (POPC). A comparative analysis of the200ns MD run on both models shows that mutant trajectories deviate from those ofwt RHO. One parameter that account for these differences is the distancebetween helix 3 (TM3) and 6 (TM6) at the cytoplasmic side. Another indicationof the structural discrepancy is the relative orientation of the monomers. Theseresults are employed to predict the effect these changes could have in bindingG-protein, the signaling pathway event following RHO's light-activation. Ourconclusion is that this single mutation alters wt RHO structure enough toimpede a functional coupling with the G-protein.<!-- /* Font Definitions */@font-face{font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1107305727 0 0 415 0;}@font-face{font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;mso-font-alt:Calibri;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-520092929 1073786111 9 0 415 0;} /* Style Definitions */p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin-top:0cm;margin-right:0cm;margin-bottom:10.0pt;margin-left:0cm;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;color:#00000A;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}p.MsoFooter, li.MsoFooter, div.MsoFooter{mso-style-priority:99;mso-style-link:"Pie de página Car";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;tab-stops:center 220.95pt right 441.9pt;font-size:10.0pt;mso-bidi-font-size:11.0pt;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}span.PiedepginaCar{mso-style-name:"Pie de página Car";mso-style-priority:99;mso-style-unhide:no;mso-style-qformat:yes;mso-style-locked:yes;mso-style-link:"Pie de página";}span.PiedepginaCar1{mso-style-name:"Pie de página Car1";mso-style-noshow:yes;mso-style-priority:99;mso-style-unhide:no;mso-ansi-font-size:11.0pt;color:#00000A;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-size:10.0pt;mso-ansi-font-size:10.0pt;mso-bidi-font-size:11.0pt;font-family:Calibri;mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}size:612.0pt 792.0pt;margin:70.85pt 3.0cm 70.85pt 3.0cm;mso-header-margin:0cm;mso-footer-margin:35.4pt;mso-forms-protection:no;mso-paper-source:0;}div.WordSection1{page:WordSection1;mso-endnote-numbering-style:arabic;}