Involvement of G proteins and cAMP in the production of chitinolytic enzymes by Trichoderma harzianum

Abstract

The effect of G protein modulators and cyclic AMP (cAMP) on N-acetylglucosaminidase (NAGase) production was investigated during 84 h of growth of a Trichoderma harzianum strain in chitin-containing medium. Caffeine (5 mM), N 6 2-O-dibutyryladenosine 35-cyclic monophosphate sodium salt (dBcAMP) (1 mM) and 3-isobutyl-1-methylxanthine (IBMX) (2 mM) decreased extracellular NAGase activity by 80%, 77% and 37%, respectively. AlCl3/KF (100 µM/10 mM and 200 µM/ 20 mM) decreased the activity by 85% and 95%, respectively. Cholera (10 µ/mL) and pertussis (20 µ/mL) toxins also affected NAGase activity, causing a decrease of approximately 75%. Upon all treatments, protein bands of approximately 73 kDa, 68 kDa and 45 kDa had their signals diminished whilst a 50 kDa band was enhanced only by treatment with cholera and pertussis toxins. N-terminal sequencing analysis identified the 73 kDa and 68 kDa proteins as being T. harzianum NAGase in two different truncated forms whereas the 45 kDa band comprised a T. harzianum endochitinase. The 50 kDa protein showed sequence similarity to Coriolus vesicolor cellobiohydrolase. The above results suggest that a signaling pathway comprising G-proteins, adenylate cyclase and cAMP may be involved in the synthesis of T. harzianum chitinases.

Neuronal differentiation by indomethacin and IBMX inhibits proliferation of small cell lung cancer cells in vitro

“…The phosphodiesterase inhibitor IBMX causes an increase of intracellular cyclic adenosine monophosphate (cAMP) [31] and has been shown to inhibit growth and induce both differentiation and apoptosis of malignant gliomas in vitro [32]. Concerning lung cancer, cAMP induction obviously leads to differential effects: whereas we (data not shown) and others demonstrate that an increase of intracellular cAMP is associated with a reduced cell proliferation of SCLC cells [33], it has been shown that lung adenocarcinoma are stimulated in their growth by agents that increase cAMP [34], so that the inhibitory effects of IBMX might be cell type specific for SCLC cells.…”

Characterization of a chitinase with antifungal activity from a native Serratia marcescens B4A

“…Since chitin is the major component of most fungal cell walls, a principal role has been attributed to enzymes from the chitinolytic system (12). Enzymatic lysis of fungal cell walls through extracellular chitinases has been implicated as a mechanism of biocontrol by bacterial agents (24,63,64).…”