Mustafa Erbakan


I am a PhD student in Curtis Lab since August 2008. I have received my BSc and MSc at Cukurova University in Turkey. My previous research areas were kinetics of antioxidant enzymes and membrane bound guanylate cyclases in visual transduction. After working at Adiyaman University as research assistant in 2007, I have won a scholarship from Turkish Republic, Ministry of National Education to attend Penn State and pursue a PhD degree in Protein Production Technologies.

Research Project

My project is related to develop Rhodobacter sphaeroides (R. sphaeroides) as an alternative bacterial platform for functional expression of medically relevant membrane proteins. Membrane proteins carry out extremely important roles for any kind of organisms including transportation of solutes and water in and out of the cells, signal transduction, cell-cell adhesion, energy generation etc. Not surprisingly, majority of the drugs on market today, directly or indirectly, target membrane proteins to regulate their activity. Despite their extreme importance, membrane proteins of known structure are quite minute compared to their soluble counterparts. Low abundance of membrane proteins in natural sources and poor performance of heterologous expression systems hinder obtaining higher amounts of membrane proteins for structural and functional studies. Membrane proteins require a lipid bioenvironment to retain their 3D structure and functionality. Expression platforms like E.coli have limited membrane surface area to accommodate heterologously expressed membrane proteins. Thus, these proteins either end up in inclusion bodies losing their 3D structure or create toxicity problems for the host. R.sphaeroides is a photosynthetic bacteria with 15 times larger membrane surface area than E.coli provided by inducible intracellular membranes (ICM) holding photosynthetic apparatus. We employ native photosynthetic promoters to synchronize membrane protein expression with ICM synthesis. Thus heterologously expressed membrane proteins target ICMs and retain their 3D structure. A variety of disease linked human membrane proteins of different membrane spanning domains such as tight junction protein, occludin and aquaporins are currently being produced at mg/L levels. The next level of the study aims the scaling up of membrane protein expression employing a photobioreactor to solve light limitations experienced by high density cultures.