Identificação de um peptideo antifúngico em sementes de Passiflora alata Curtis com similaridade à albumina 2S

Abstract

Diseases caused by pathogens, including bacteria and fungi can generate many problems to human health and agriculture. In important economically cultivars, such pathogens may contribute to significant losses in yield of agricultural production. The aggravating factor for these two scenarios is the intensive use of conventional compounds to combat these pathogens, leading to selection of highly resistant microorganisms. Furthermore, these compounds can bring severe consequences to the environment, human and animal health. Thus the search for new compounds capable of effectively controlling bacteria and fungi resistant has been a priority. In this report a heterodimeric antifungal protein named Pa-AFP1, showing higher identity with the 2S albumin family, was purified by using 70-100% ammonium sulfate saturation and further purification steps such as anionic exchange Q-Sepharose chromatography associated with HPLC reversed-phase C4 chromatography. Analysis by Tricine-SDS-PAGE revealed two peptide molecular masses of approximately 4,500 Da and 7,000 Da, in the presence of β-mercapthoetanol, while by removing the reducing agent, a single protein with molecular mass of about 11,500 Da was obtained. Moreover, dimeric mass was confirmed by MALDI-TOF analyses (11,569.76 Da). The antifungal protein, named Pa-AFP1, efficiently inhibited the growth of filamentous fungi Colletotrichum gloeosporiodes, and was added to a short list of 2S albumins with antimicrobial properties. Otherwise, this same peptide showed no activity toward bacteria and yeasts. In summary, this compound could be used in the future to develop biotechnological products for the control of phytopathogenic fungi.