Drastic Genome Reduction in an Herbivore's Pectinolytic Symbiont.
Cell
; 171(7): 1520-1531.e13, 2017 Dec 14.
Article
en En
| MEDLINE
| ID: mdl-29153832
ABSTRACT
Pectin, an integral component of the plant cell wall, is a recalcitrant substrate against enzymatic challenges by most animals. In characterizing the source of a leaf beetle's (Cassida rubiginosa) pectin-degrading phenotype, we demonstrate its dependency on an extracellular bacterium housed in specialized organs connected to the foregut. Despite possessing the smallest genome (0.27 Mb) of any organism not subsisting within a host cell, the symbiont nonetheless retained a functional pectinolytic metabolism targeting the polysaccharide's two most abundant classes homogalacturonan and rhamnogalacturonan I. Comparative transcriptomics revealed pectinase expression to be enriched in the symbiotic organs, consistent with enzymatic buildup in these structures following immunostaining with pectinase-targeting antibodies. Symbiont elimination results in a drastically reduced host survivorship and a diminished capacity to degrade pectin. Collectively, our findings highlight symbiosis as a strategy for an herbivore to metabolize one of nature's most complex polysaccharides and a universal component of plant tissues.
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Base de datos:
MEDLINE
Asunto principal:
Escarabajos
/
Genoma Bacteriano
/
Enterobacteriaceae
Idioma:
En
Revista:
Cell
Año:
2017
Tipo del documento:
Article