The iron-responsive regulator Fur of Campylobacter jejuni is expressed from two separate promoters

Abstract

A lacZ-based reporter gene system was used to identify the promoter of the Campylobacter jejuni iron-responsive gene regulator Fur. In other Gram-negative bacteria, the fur promoter is usually located directly upstream of the fur gene and is often autoregulated in response to iron. In this study we demonstrate that expression of the C. jejuni fur gene is controlled from two promoters located in front of the first and second open reading frames upstream of fur. Neither of these promoters was iron-regulated, and the presence of both promoters in front of fur gives higher expression of the lacZ reporter than with either promoter alone. Expression from two distal promoters might be a mechanism for regulating the level of the C. jejuni Fur protein in response to unknown stimuli.