The present invention relates to a polypeptide with an amino acid sequence according to SEQ ID NO: 1 and fragments or derivatives thereof. The present invention further relates to fusion proteins comprising said polypeptide and an additional peptide stretch fused to said polypeptide at the N- or C-terminus. Moreover, the present invention relates to nucleic acid molecules encoding said polypeptide or fusion protein, vectors comprising said nucleic acid molecules and host cells comprising either said nucleic acid molecules or said vectors. In addition, the present invention relates to said polypeptide or fusion protein for use as a medicament, in particular for the treatment or prevention of Gram-negative bacterial infections, as diagnostic means, as cosmetic substance or as sanitizing agent. The present invention also relates to the use of said polypeptide or fusion protein for the treatment or prevention of Gram-negative bacterial contamination of foodstuff, of food processing equipment, of food processing plants, of surfaces coming into contact with foodstuff, of medical devices, of surfaces in hospitals and surgeries. Furthermore, the present invention relates to a pharmaceutical composition comprising said polypeptide or fusion protein.La présente invention concerne un polypeptide de séquence dacides aminés conforme à SEQ ID NO: 1 et ses fragments ou dérivés. La présente invention concerne en outre des protéines de fusion comprenant ledit polypeptide et une autre séquence peptidique fusionnée audit polypeptide à lextrémité N- ou C-terminale. En outre, la présente invention concerne des molécules dacide nucléique codant ledit polypeptide ou ladite protéine de fusion, des vecteurs comprenant lesdites molécules dacide nucléique et des cellules hôtes comprenant lesdites molécules dacide nucléique ou lesdits vecteurs. De plus, la présente invention concerne lutilisation dudit polypeptide ou de ladite protéine de fusion comme médicament, en particulier pour le traitem
