一氧化氮在启动黄孢原毛平革菌木质素降解酶合成中的作用

Function of nitric oxide in initiating production of lignin degrading peroxidases by Phanerochaete Chrysosporium

摘要:

摘要:【目的】通过了解一氧化氮在启动黄孢原毛平革菌合成木质素过氧化物酶(LiP)中的作用及其作用机制，弄清白腐菌启动次生代谢的调控机制。【方法】以黄孢原毛平革菌原种pc530及突变种pcR5305为研究对象，弄清在不同营养条件下NO含量的动态变化及其与合成LiP之间的关系，再通过添加外源NO供体SNP、NO淬灭剂cPTIO对两菌株合成LiP 的影响分析，揭示NO在白腐菌启动合成LiP中的作用和作用机理。【结果】两菌株均能在两种不同营养条件下产生NO，但NO的产生量与菌株及其营养状况有关，富营养使pc530 产生NO量低且严重延后，而pcR5305产生NO并不需要营养饥饿激发且产生量显著高于pc530。除了LiP峰值出现时间迟于NO峰值时间外，NO含量与LiP合成呈正相关性;外施SNP对合成LiP有促进作用，但对pcR5305的促进作用没有pc530明显;15 mmol/L cPTIO使黄孢原毛平革菌合成LiP均大为降低，但并没有完全抑制产生LiP。【结论】黄孢原毛平革菌可能通过产生NO 启动LiP的合成，但NO并不直接参与或影响合成LiP，NO更可能是作为一种上游的信号分子起作用。除了NO外，可能还有其它与NO有相互促进作用的信号分子也参与了LiP合成的调控。与pc530具有不同的产生NO的机制可能就是pcR5305抗营养阻遏合成木质素降解酶的机理。

Abstract:

Abstract:［Objective］By analyzing the function and mechanism of nitric oxide in initiating producing lignin peroxidases by phanerochaete chrysosporium，we studied the regulation mechanism triggering the secondary metabolism of white-rot fungi．［Methods］Mutant (pcR5305) and wild-type (pc530) strains of phanerochaete chrysosporium were respectively cultured under both the conditions of nitrogen limitation and nitrogen sufficiency． To compare their lignin peroxidases (LiP)-production and nitric oxide(NO)-production kinetics and their different influences on producing LiP after the NO donor Sodium Nitroprusside (SNP) and scavenger cPTIO were respectively added to the nitrogen limitation or sufficiency culture medium to show the function and mechanism of nitric oxide in initiating production of lignin peroxidases by whiterot fungi．［Results］Both strains produced nitric oxide (NO) under the two opposite nutritional conditions，but the levels of NO produced were related with the type of strain and the nutritional conditions．Strain pc530 produced NO requiring nutrition depletion and producing of NO was strongly delayed and reduced when it was cultured under nitrogen sufficiency condition．On the contrary，pcR5305 did not require nitrogen depletion to trigger and the levels of NO were higher than that of pc530． The results indicate that LiP content had positive correlation with NO value except the occurrence time of LiP peak value was later than that of NO． The ability of producing LiP was promoted after the NO donor SNP added，but SNP affected more on pc530 than pcR5305 in promoting producing LiP． 15mM cPTIO would greatly repress producing LiP，but could not completely restrain the synthesis of LiP for both strains.［Conclusion］ By producing NO，Phanerochaete chrysosporium triggers LiP synthesis． However，the evidences do not indicate that NO participates or effect directly in LiP synthesis．It is more likely that NO is reacting as an upstream signal molecule． Besides NO，there are other signal molecules that have a positive effect on NO levels also involving in the regulation producing LiP． The mechanism of the resistance to nutritional repression of pcR5305 in synthesizing lignin degrading peroxidases may be the answer to the different NO production mechanism of pcR5305 from pc530.