Proteomic Analysis Of Biological Affects On Streptococcus Pneumoniae Induced By Manganese Depression

Manganese is necessary for survival and infection for many pathogenic microorganisms. However, the concentration of manganese ions is very low in host environment, ranging from tens of nanomolar to micromolar, making it very hard for pathogenic microorganisms to intake sufficient manganese for infection. Streptococcus pneumoniae is a common pathogenic microorganism, causing various human diseases including pneumonia, otitis media and bacterial meningitis. It has been reported that an important ABC type manganese transporter called PsaABC exists in this specie, in which PsaA is a receptor of the metal ions located outside of the bacterial membrane. Deletion of PsaA affects the growth and virulence of Streptococcus pneumoniae negatively.AIM:To analyze how manganese affects Streptococcus pneumoniae by using proteomics methods, including the effects of the manganese lacking environment and PsaA deletion.METHODS:Wide-type D39 strain of the bacteria was cultured in THY medium with or without manganese, total proteins and membrane proteins of the bacteria were collected for inter-class comparison. D39 strain and PsaA deletion mutant strain of the bacteria were cultured in normal THY medium and their protein expressions were compared.RESULTS:In D39 strain of Streptococcus pneumoniae cultured in the absence of manganese,29 down-regulated and 3 up-regulated proteins were found in its total proteome, while 15 down-regulated and 3 up-regulated proteins were identified in its membrane protein fraction. For the bacteria cultured in the absence of manganese, the intracellular iron concentration increased to about double amount. In PsaA deletion mutant strain,50 proteins down-regulated and 24 up-regulated.CONCLUSIONS:Lacking of environmental manganese resulted in the down-regulation of many proteins, including enzymes of metabolism, transporters of carbohydrate and peptides, and ribosome proteins. In addition, Streptococcus pneumoniae can intake more iron when no enough manganese is available. PsaA is an important protein; its absence resulted in not only the declination of the intracellular manganese, but also changes of protein expression.