A. Residues selected for cysteine replacement mapped onto the secondary structure of the Aer PAS domain. Residues in black font are predicted to be accessible on the surface of the Aer-PAS homology model; those in red font are predicted to face inwards towards the PAS interior, and were selected as surface-inaccessible controls.
B. Extent of PEGylation for substituted cysteines in the Aer PAS core and N-terminal cap (N-cap). Red asterisks identify the surface-inaccessible controls.
C. Extent of disulfide crosslinking between neighboring PAS domains. Error bars in B and C represent the standard deviation from multiple experiments.
D. Aer-PAS homology model showing the distribution of the tested residues based on whether they had low (yellow shading, 0–30% PEGylation), intermediate (light orange, 31–50% PEGylation) or high (orange, >50% PEGylation) accessibility.