posted on 2016-02-19, 13:49authored byPauline Krijgsheld, Benjamin
M. Nitsche, Harm Post, Ana M. Levin, Wally H. Müller, Albert J. R. Heck, Arthur
F. J. Ram, A. F. Maarten Altelaar, Han A. B. Wösten
Aspergillus niger is a cell
factory for the production of enzymes. This fungus secretes
proteins in the central part and at the periphery of the colony. The
sporulating zone of the colony overlapped with the nonsecreting subperipheral
zone, indicating that sporulation inhibits protein secretion. Indeed,
strain ΔflbA that is affected early in the
sporulation program secreted proteins throughout the colony. In contrast,
the ΔbrlA strain that initiates but not completes
sporulation did not show altered spatial secretion. The secretome
of 5 concentric zones of xylose-grown ΔflbA colonies was assessed by quantitative proteomics. In total 138 proteins
with a signal sequence for secretion were identified in the medium
of ΔflbA colonies. Of these, 18 proteins had
never been reported to be part of the secretome of A. niger, while 101 proteins had previously not been identified in the culture
medium of xylose-grown wild type colonies. Taken together, inactivation
of flbA results in spatial changes in secretion and
in a more complex secretome. The latter may be explained by the fact
that strain ΔflbA has a thinner cell wall compared
to the wild type, enabling efficient release of proteins. These results
are of interest to improve A. niger as a cell factory.