¹H, ¹³C, ¹⁵ N backbone and side-chain NMR assignments for three MAX effectors from Magnaporthe oryzae

Area of Science:

• Plant Pathology
• Molecular Biology
• Structural Biology

Background:

• Fungal effectors, including MAX effectors, are secreted proteins translocated into plant cells during infection.
• MAX effectors share a conserved fold topology despite sequence divergence and are produced by Magnaporthe fungi, pathogens causing significant rice crop losses.
• Understanding MAX effectors is critical for combating phytopathogens and developing disease-resistant rice varieties, addressing global food security concerns.

Purpose of the Study:

• To perform near-complete nuclear magnetic resonance (NMR) resonance assignment for three new putative MAX effectors (MAX47, MAX60, and MAX67).
• To determine the secondary structure of these MAX effectors and compare it to the known canonical structure.
• To lay the groundwork for further structural characterization and improve sequence-based predictions of MAX effectors.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 15N, and 13C) was used for resonance assignment.
• TALOS-N and CSI.3 software were employed for secondary structure determination.
• Bioinformatic data mining approaches will be utilized in subsequent studies.

Main Results:

• Near-complete 1H, 15N, and 13C NMR resonance assignments were obtained for MAX47, MAX60, and MAX67.
• Secondary structure analysis revealed a high content of beta-strands in all three proteins.
• The determined secondary structures are consistent with the canonical beta-sandwich fold of MAX effectors.

Conclusions:

• The study provides foundational NMR assignments and secondary structure information for novel MAX effectors.
• The findings support the conserved beta-sandwich structural motif within the MAX effector family.
• This work facilitates future detailed structural studies and enhances the potential for computational prediction of effector functions.