AUTOINDUCTION OF THE EXPRESSION OF THE RECOMBINANT FORMS OF THE THREE GLOBULAR FRAGMENTS CONSTITUTING gC1q

Human C1q is a glycoprotein with a complex biochemical structure. It was first known for its classical function as the recognition molecule of the classical complement pathway. But recently the functional scope of C1q was revealed to include immunomodulatory activity in many aspects of human homeostasis. Considerable part of C1q functionality is realized by its globular heads each of which consists of the globular head fragments of the three polypeptide chains A (ghA), B (ghB) and C (ghC), respectively. The globular head fragments ghA, ghB and ghC have been shown to exhibit functional independence within the globular head so they were termed modules. The use of recombinant analogues of the three modules expressed as fused proteins with the bacterial maltose binding protein (MBP) made it possible to reveal the functional diversity of the whole molecule. The routine expression of the modules is achieved by IPTG induction. We compared the effectiveness of a new approach for protein expression, namely autoinduction with the routine one. Autoinduction proved to be preferable for the expression of MBP-ghC in terms of better yield and MBP-ghB in terms of better quality of the protein preparation. For MBP-ghA we found that autoinduction was equally effective with IPTG induction.