10 August 2007 Nobel Prize Winner to give public lecture at Lincoln University

The Canterbury public has the opportunity to hear Nobel Prize winner in Chemistry Sir John Walker of Cambridge at a free public lecture at Lincoln University on 3 September.

Sir John, who won his Nobel award in 1997 along with two co-laureates, is Director of the UK Medical Research Council’s Dunn Human Nutrition Unit in Cambridge, England.

The lecture is in Lincoln University’s Stewart 2 lecture theatre, starting at 6.30pm.

The topic is “Rotary Machines in Biology” and Sir John will discuss his work on the molecular structure and mechanism of rotary machines responsible for maintaining life in organisms.

The “rotary machine” description is used for these nano-sized cellular structures because that is how they are most appropriately characterised. They have energy inputs and outputs, turbine-like drive mechanisms and other machine-like features.

Sir John's share of the 1997 Nobel Prize was for his study of adenosine triphosphate (ATP) synthase, the first of the biological rotary machines to be understood.

The ATP synthase is a multi-subunit enzyme system which produces adenosine triphosphate, the main carrier of chemical energy in living organisms, from bacteria and fungi to plants and animals. 

Sir John’s work provided the structural information that revealed the mechanism by which the system operates and it confirmed the binding change mechanism postulated by co-laureate, Professor Paul Boyer of the University of California. 

The work of the pair fitted with that of the third co-laureate, Professor Jens Skou of Aarhus University, Denmark, who studied a related enzyme, sodium/potassium ATPase, responsible for maintaining the balance of sodium and potassium ions in the living cell.

ATP synthase is a nano-sized molecular machine, made of 16 different proteins and powered by the discharge of an electrical (proton) gradient across a membrane. This gradient is discharged through a turbine in the membrane which rotates at about 6000 rpm and is attached to an asymmetric drive shaft. Rotation of this shaft causes conformational changes in the catalytic portion of the enzyme complex and stamps out ATP by squeezing adenosine diphosphate and inorganic phosphate together.

Similar machines run in reverse, with the hydrolysis of ATP powering the pumping of protons and other ions.

Since the Nobel award Sir John’s interest has broadened to other molecular machines with similar structures and mechanics that carry out a diverse range of biological activities. These include the bacterial flagellum and machines involved in packaging DNA and RNA into viruses, and in separating DNA strands during replication and recombination. These machines have many similar elements reflecting common evolutionary origins.

Their structures, mechanisms and origins will be described by Sir John in his lecture, and the possible implications for the design of man-made rotary nano-machines will be discussed.

A number of New Zealanders have worked with Sir John over the years. 

His connection with Lincoln University arises from a long collaboration with Professor David Palmer of the Agriculture and Life Sciences Division’s Cell Biology Group. Professor Palmer’s discovery of the abnormal storage of one of the subunits of ATP synthase (subunit c) in Batten Disease was quickly recognised as important by Professor Walker when others were dubious. 

Working together with colleagues, notably Dr Ian Fearnley in Cambridge, and Professor Bob Jolly at Massey University, Walker and Palmer extended this finding to the human forms of this group of fatal inherited neurodegenerative diseases and fully characterised this difficult-to-work-with protein.

Subunit c is the key component of the turbine driving ATP synthase, the rotor being a ring of 10 subunit c molecules. Professor Walker led the subunit c genetic investigation in Batten disease in collaboration with Professor Bob Jolly at Massey. Over the years they, Palmer and Fearnley have co-authored a number of highly cited research papers on this work.

Sir John Walker’s visit is his second to New Zealand and he is the keynote speaker at the 2007 Queenstown Molecular Biology Conference.

Ian Collins, Communications Group, Lincoln University, Canterbury, New Zealand