EXPRESSION OF RETICULOMYXA-FILOSA ALPHA-TUBULIN AND BETA-TUBULIN IN ESCHERICHIA-COLI YIELDS SOLUBLE AND PARTIALLY CORRECTLY FOLDED MATERIAL

Tubulins are highly conserved multidomain proteins that have to intera ct with eukaryotic chaperonins to gain their correct three-dimensional conformation. The prokaryotic chaperonin system of GroEL/ES is able t o generate intermediate folding states but not natively folded tubulin . To create a system for studying these folding intermediates, tubulin s from the giant amoeba Reticulomyxa filosa (alpha 2- and beta 2-tubul in) were expressed in Escherichia coli singly or in tandem. In all cas es, soluble tubulin was generated in amounts of 5-10 mg/l culture. Thi s is the first reported expression of soluble tubulin in bacterial cel ls. Of particular interest was the observation that upon coexpression with R filosa beta 2-tubulin, proteolytic degradation of alpha 2-tubul in was reduced and more full-length product remained intact. This obse rvation points to a specific interaction of alpha 2- and beta 2-tubuli ns in the E. coli cell. The sites of interaction are most probably the same that are responsible for the binding of native alpha 2- and beta 2-tubulin. The established expression system therefore seems well sui ted for further studies concerning the folding of tubulins. (C) 1998 E lsevier Science B.V. All rights reserved.