Phospholipase A2 in salivary glands isolated from tobacco hornworms, Manduca sexta

Abstract

We describe a phospholipase A2 (PLA2) associated with the salivary glands of tobacco hornworms, Manduca sexta. This enzyme is able to hydrolyze arachidonic acid from the sn-2 position of PLs. Addition of the calcium chelator, EGTA, or calcium, to the Tris reaction buffer impaired the PLA2 activity, from which we infer the enzyme requires very low concentrations of calcium or perhaps other ions for optimal activity. PLA2 activity was sensitive to protein concentration (highest activity at 25 μg protein per μl), reaction time (optimal at 30 min), buffer pH (optimal at pH 8-10), and reaction temperature (optimal range 18-38°C). The salivary gland PLA2 was sensitive to the site-specific inhibitor, oleyloxyethylphosphorylcholine and stable to freezing at -80°C, but not -20°C. The biological significance of this enzyme may relate to hydrolysis of fatty acid moieties from dietary PLs for absorption by midgut epithelia. This salivary gland enzyme may also be responsible for killing foodborne bacteria.

Comparative Transcriptome Analysis of Salivary Glands of Two Populations of Rice Brown Planthopper, Nilaparvata lugens, That Differ in Virulence

“…A recent study showed that a salivary lipase (MdesL1) of Mayetiola destructor was involved in extra-oral digestion and host cell permeability [41] . In another study, phospholipase A 2 in the salivary glands of Manduca sexta may have been involved in the hydrolysis of fatty acid moieties from dietary phospholipids and also in killing food-borne bacteria [42] . The functional characterization of these hydrolases and of the digestive enzymes of the BPH may shed light on this species' mode of extra-oral digestion and plant defense suppression.…”

The effect of diet on the expression of lipase genes in the midgut of the lightbrown apple moth (Epiphyas postvittana Walker; Tortricidae)

“…Since no ESTs characteristic of classical phospholipases have been reported from lepidopteran midgut, it is likely the phospholipase A2 activities that have been characterized from the midgut and salivary gland of Manduca sexta (Stanley et al. , 1998; Rana & Stanley, 1999; Tunaz & Stanley, 2004) are pancreatic lipases.…”

“…, 2009) and phospholipase A2 (Stanley et al. , 1998; Rana & Stanley, 1999; Tunaz & Stanley, 2004) activities from lepidopteran larval midgut, fat body and salivary gland, and lipase and phospholipase activities from Coleoptera, Diptera and Hemiptera (Uscian et al. , 1995; Nor Aliza & Stanley, 1998; Pistillo et al.…”

Transcriptome analysis of the salivary glands of potato leafhopper, Empoasca fabae

“…Lipases are multifunctional proteins involved in lipid acquisition, storage and mobilization besides their involvement in reproduction and development (Mamidala et al, 2011a;Horne et al, 2009). Lipases perform a diverse and unique array of functions in insects and are well documented in several blood feeding insects, however, these are poorly understood in phytophagous insects (Arrese and Soulages, 2010;Tunaz and Stanley, 2004;Anderson et al, 2006). In a recent study of Mayetiola destructor, a lipase salivary transcript (MdesL1) was shown to be involved in extra-oral digestion and host cell permeability (Anderson et al, 2006).…”