Thomas Steitz

No­bel Prize-win­ning chemist

The Scotsman - - Obituaries - GINA KOLATA

Thomas Steitz, a tow­er­ing fig­ure of late-20th-cen­tury science who shared a No­bel Prize in chem­istry for fig­ur­ing out the struc­ture of a huge mol­e­cule cen­tral to trans­lat­ing the ge­netic code into the pro­teins that make up liv­ing mat­ter, died on Tues­day at his home in Bran­ford, Con­necti­cut. He was 78.

Steitz was guided by the vi­sion of a grand project to find the struc­tures not just of that mol­e­cule but also of all the large mol­e­cules in­volved in trans­lat­ing ge­netic in­for­ma­tion into pro­teins, the so­called cen­tral dogma of molec­u­lar bi­ol­ogy. His No­bel, awarded in 2009, was for his dis­cov­ery of the ex­act size, shape and po­si­tion of ev­ery atom in the ri­bo­some, the large mol­e­cule that is the site of such cru­cial protein syn­the­sis.

One im­me­di­ate ap­pli­ca­tion of the dis­cov­ery was in un­der­stand­ing how a ma­jor set of an­tibi­otics – those that poi­son bac­te­rial ri­bo­somes – work, thus of­fer­ing clues to find­ing an­tibi­otics that can evade drug-re­sis­tant bac­te­ria.

He also found the struc­tures of the other mol­e­cules that are part of the cen­tral dogma.

“He could have been given three No­bels,” Don­ald En­gel­man, a fel­low bio­physi­cist at Yale and a good friend, said. “Even if he had never done the ri­bo­some, if there was some­thing called the ca­reer No­bel Prize he would have been a win­ner.”

The prob­lems Steitz solved were “daunt­ing,” said an­other friend, Thomas Cech of the Uni­ver­sity of Colorado at Boul­der, who shared the chem­istry No­bel in 1989.

Steitz, he added, had “a tal­ent that is in­de­scrib­able.”

Thomas Arthur Steitz was born in Mil­wau­kee on 23 Au­gust 1940, the old­est of five chil­dren. His fa­ther, Arthur, was in charge of per­son­nel at the Mil­wau­kee County Hospi­tal. His mother, Cather­ine (Brown) Steitz, took care of Tom and his si­b­lings.

Steitz re­ceived a full schol­ar­ship to Lawrence Col­lege, in Ap­ple­ton, Wis­con­sin, where his teacher Robert Rosen­berg, a shap­ing in­flu­ence on him, in­tro­duced him to chem­istry.

“I still re­call the early lec­tures in his in­tro­duc­tory chem­istry course, where he in­tro­duced to us the con­cepts of atomic or­bitals and bond­ing and how study­ing chem­istry at the phys­i­cal chem­i­cal atomic level al­lowed us to un­der­stand the prop­er­ties of chem­i­cals, such as their colour,” Steitz wrote. “It was a won­der­ful rev­e­la­tion to me about how the world around me could be un­der­stood.”

De­ter­mined to con­tinue his stud­ies, he went to Har­vard for grad­u­ate school. There, in 1963, he heard a lec­ture that changed his life. It was given by Max Perutz, a renowned sci­en­tist who had shared the 1962 No­bel Prize in chem­istry with col­league John Cow­dery Ken­drew for dis­cov­er­ing a way to de­ter­mine the po­si­tions of all the atoms in large protein mol­e­cules. It was a ma­jor ad­vance be­cause it al­lowed sci­en­tists to make de­tailed molec­u­lar mod­els of pro­teins and see which ar­eas were im­por­tant and why.

The idea was to make crys­tals out of a mol­e­cule and then bom­bard the crys­tals with X-rays. The X-rays bounce off the atoms that make up the crys­tals; by ob­serv­ing the pat­tern of the re­flected X-rays, it is pos­si­ble to de­ter­mine the po­si­tion of each atom.

Steitz wrote that he was stunned by Perutz’s lec­ture, which fea­tured a three-di­men­sional im­age of am yo glob in mol­e­cule that had been pro­duced by Ken­drew.

A friend at Yale, Peter Moore, a chem­istry pro­fes­sor, at­tended the same lec­ture. “It was a mind-blow­ing event,” Moore said. “It was the first time I ever saw an atomic res­o­lu­tion pic­ture of a protein in three di­men­sions. The im­age was in stereo, and it was about the size of a small blimp. Here was this lit­tle man stand­ing un­der this im­age that seemed to be float­ing over our heads in the mid­dle of the room.”

Steitz de­cided then and there to be­come an X-ray crys­tal­lo­g­ra­pher. He joined a group led by William Lip­scomb, the only sci­en­tist at Har­vard us­ing that tech­nique. Lip­scomb was awarded the chem­istry No­bel Prize in 1976.

Af­ter Har­vard, Steitz spent three years at the Med­i­cal Re­search Coun­cil Lab­o­ra­tory of Molec­u­lar Bi­ol­ogy in Cam­bridge, where Perutz, Ken­drew and other gi­ants in molec­u­lar bi­ol­ogy and bio­physics worked. Among them were Fran­cis Crick, who shared the 1962 No­bel in medicine or phys­i­ol­ogy with James Wat­son; Syd­ney Bren­ner, who shared the medicine No­bel in 2002; Fred­er­ick Sanger, who won the chem­istry No­bel in 1958 and shared that prize in 1980; and Richard Henderson, who shared the chem­istry No­bel in 2017.

Steitz was in Cam­bridge when he de­cided to fo­cus on the cen­tral dogma of molec­u­lar bi­ol­ogy by find­ing the struc­tures of the rel­e­vant mol­e­cules. “He had a vi­sion that was pre­ma­ture,” Henderson said. “But he stuck with it, and then all the meth­ods caught up and al­lowed him to achieve his vi­sion.”

Af­ter Cam­bridge, Steitz be­gan a long ca­reer at Yale, which also hired his wife, Joan Ar­getsinger Steitz, an em­i­nent molec­u­lar bi­ol­o­gist.

Cech said that as an X-ray crys­tal­lo­g­ra­pher Steitz was un­matched, “the master of X-ray crys­tal­log­ra­phy in the cur­rent era”. It was at Yale, in 2000, that he fig­ured out the struc­ture of the ri­bo­some, a project that had taken five years. That was a key dis­cov­ery, Moore ex­plained, be­cause know­ing what a ri­bo­some looks like tells you how a protein is made. The ri­bo­some con­verts the DNA se­quences of genes into a se­quence of amino acids, the build­ing blocks of pro­teins.

Un­der­stand­ing the struc­ture of the ri­bo­some had an im­me­di­ate ap­pli­ca­tion to medicine. About half of all an­tibi­otics used clin­i­cally act by pre­vent­ing bac­te­rial ri­bo­somes from work­ing, while leav­ing hu­man ones alone.

Once sci­en­tists knew how to in­ter­pret the pat­tern of X-rays that bounce off a ri­bo­some crys­tal, Moore said, it was easy to fig­ure out where and how an­tibi­otics bind to bac­te­rial ri­bo­somes.

In ad­di­tion to his wife, Steitz is sur­vived by their son, Jon, two grand­chil­dren and four si­b­lings.

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