TABLE 2.
Cts1 and Cts2 degrade defined chito-oligosaccharides, but their processing mode differs
| Substrate | Detection ofa: |
Molar product ratiob |
||
|---|---|---|---|---|
| (GlcNAc)6 | (GlcNAc)4 | (GlcNAc)6 | (GlcNAc)4 | |
| AB33 | Y | Y | 8.3 ± 1.0 | 2.4 ± 0.1 |
| cts1Δ | Y | Y | 4.3 ± 0.8 | 1.3 ± 0.1 |
| cts2Δ | Y | Y | 8.2 ± 0.2 | 2.6 ± 0.2 |
| cts3Δ | Y | Y | ||
| cts1/2Δ | N | N | ||
| cts1/3Δ | Y | Y | 4.5 ± 1.4 | 1.3 ± 0.1 |
| cts2/3Δ | Y | Y | 8.3 ± 2.9 | 3.0 ± 0.2 |
| cts1/2/3Δ | N | N | ||
Incubation of chitohexamer (GlcNAc)6 or chitotetramer (GlcNAc)4 with U. maydis total protein extracts leads to production of chitodimer (GlcNAc)2 and chitotrimer (GlcNAc)3, which are detectable by HILIC-ELSD-ESI-MS (Y). This degradation is abolished in cts1Δ cts2Δ double mutants (N).
Since Cts1 and Cts2 are the only active chitinases, molar ratios between (GlcNAc)2 and (GlcNAc)3 were calculated for the deletion strains lacking either cts1 or cts2. They are reduced 2-fold in strains with Cts2 as the only active chitinase (cts1Δ and cts1/3Δ), suggesting different modes of processing for Cts1 and Cts2. Results are means and standard deviations from three independent experiments.