Using chimeras to explore protein activity: A case study of neuroglobin and myoglobin.

IGNACIO BORON, LUCÍA CHISARI, LUCIANA CAPECE, DIANA E. WETZLER, MARCELO A. MARTI, DARIO A. ESTRIN Y ALEJANDRO D. NADRA.

Sierra de la Ventana

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica; 2014

Sociedad Argentina de Biofísica

p { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); line-height: 115%; text-align: left; orphans: 2; widows: 2; }p.western { font-family: "Calibri"; font-size: 11pt; }p.cjk { font-family: "Arial Unicode MS",sans-serif; font-size: 11pt; }p.ctl { font-size: 11pt; }a:link { color: rgb(0, 0, 255); }a.western:link { }a.ctl:link { }BackgroundGlobinsare well-known proteins that generally exhibit two histidine residuesclose to the iron, so it could be expected them to coordinate theheme. Nevertheless, typical globins such as myoglobin (Mb) andhemoglobin are pentacoordinated (5c) with only one His binidng to theiron. In the last decade, however, many hexacoordinated (6c) globinswere discovered and several roles for hexacoordination in proteinfunction were proposed. We are interested in neuroglobin (Ngb), whichis expressed in the nervous system of vertebrates and whose functionis still under debate. Ourgoalis to shed light on the key determinants for heme 6c⇆5c equilibriumthat regulates globin reactivity. For this purpose we engineered Mband Ngb by swapping their CD region with the goal of exchanging the6c⇆5c equilibrium behavior. Further, a point mutant was designed toenhance coordination shift. ResultsResidue contact map and dynamic properties of parent proteins aregenerally transferred to the chimeras. Stopped flow, laser flashphotolysis and autoxidation experiments support this behaviortransfer. Altogether, our results confirm a significant role of theCD region in the modulation of the 5c⇆6c equilibrium andconsequently in globins fuction, but also suggest contributions ofother protein regions.