That phone call from Bethesda to Oklahoma City lastApril was "a once-in-a-lifetime coincidence," recalledbiochemist Ronald Conaway, "a great science story."
He and his wife, Joan Conaway, also a biochemist, hadbeen working for 10 years, he told BioWorld Today, "onisolating and characterizing a set of general transcriptionfactors, believed to be involved in transcribing all genesin the genome."
One such factor is the trimeric protein now known asElongin, which stimulates elongation of RNA in thetranscription process by the enzyme, RNA polymerase.
The couple had been "systematically isolating the genesof Elongin, which is composed of three molecularsubunits," Ronald recalled. "Then the phone rang."
Joan picked up the story: "We had actually at that pointisolated the genes for all three subunits, usingrecombinant proteins expressed in Escherichia coli toreconstitute this transcription factor. And we'd publishedthe smallest subunit, Elongin C."
On the line was National Institutes of Health cellbiologist Richard Klausner, who has since been appointeddirector of the National Cancer Institute in Washington.
"Rick told us," Joan continued, "`We have some results Ithink you'd be interested in, and I think we cancollaborate."
Klausner and his lab had been studying a protein calledVHL _ von Hippel-Lindau syndrome _ about whichneither Conaway knew anything at the time.
Klausner told them about "the interesting tumorsuppressor gene and the protein it encodes," Joancontinued. "And that they had been looking for proteinsthat interact with the VHL. They had two small proteinsthat were roughly the size of our two, now called ElonginB and C. The smaller of their two had a peptide sequencethat matched our published one.
"So Klausner asked us if we had cloned the other twoElongin subunits. We had, so he said: `Let us send youour peptide sequence from the larger of the two subunits.'
Structure Meets Function To Spark Collaboration
"So we compared sequences," Joan said, "and much toour mutual delight, both our Elongin, with the B and C,contained peptides that matched their two small VHLpolypeptides. And that was where our collaborationbegan."
Von Hippel-Lindau syndrome is a rare but devastatingdisease, which can run in families or strike sporadically.It affects an estimated one in 36,000 to 39,000 individualsin the population. What it affects them with issusceptibility to renal-cell carcinoma, the commonestform of adult kidney cancer, and an associated spectrumof related malignancies, notably pheochromocytoma, andcerebellar hemangioblastoma.
What these afflictions have in common is a mutation inthe VHL gene, which Klausner was studying. So were theConaways, without fully realizing it.
"If Klausner's lab had pulled the VHL protein out, withthe small peptides on it, and cloned the gene," saidRonald, "in a million years they probably wouldn't havefigured out that these are elongation factors."
To which Joan added, "And we would never have figuredout that these Elongin proteins of ours interact with theirVHL proteins. On the one hand, it sets the direction forwhat future experiments need to be done."
She continued, "On the other hand, understanding theinteractions among Elongin's three subunits, and withVHL, puts important tools in our hands for findingpeptides or other types of drugs that may block theseinteractions _ which is possibly what VHL itself isdoing."
In its unmutated, benign mode, VHL acts as a tumorsuppressor. Mutated, it triggers those hereditary andsporadic cancers by mechanisms only beginning to beelucidated.
Both Conaways are on the scientific staff of the privatelyendowed Oklahoma Medical Research Foundation. NIHgrants support their work, and their serendipitouscollaboration with Klausner's group continues.
It's marked by a publishing milestone: The Sept. 8, 1995,issue of Science carries three papers and an editorialdevoted to the present state of Elongin research. Klausneris senior author of one, titled: "Inhibition of transcriptionelongation by the VHL tumor suppressor protein," withboth Conaways among its co-authors.
Ronald is senior author of the second article, "Elongin(SIII): A multisubunit regulator of elongation by RNApolymerase II," with Joan Conaway as co-author.
The third, by William Kaelin Jr. of Boston's Dana FarberCancer Institute, reports "Binding of the von Hippel-Lindau Tumor Suppressor Protein to Elongin B and C."
"Kaelin was the first to show," said Ronald, "that onecould reintroduce normal VHL back into renal-cellcarcinomas, put those cells back into mice, and block thetumors. It was the first classical demonstration of tumorsuppression by the VHL gene."
Summing up the near-future stage of their researchcollaboration, Ronald observed: "We're biochemists; westudy the structure and function of proteins. On the otherside, we're engaged in seeking mutants of the Elonginsubunits, trying to find out, for example, which parts of Band C are required for their interaction with VHL, andwhich for Elongin A.
"Our ultimate goal is to figure out ways to disrupt thatinteraction, so we're now making a mad dash to make asmany mutants as possible to deal with the separatefunctions."
Joan concluded, "Or likewise, by finding which parts ofElongin B and C interact with A, we may be able todesign therapeutics that mimic the tumor-suppressoreffect of VHL." n
-- David N. Leff Science Editor
(c) 1997 American Health Consultants. All rights reserved.