FIG 4 .

Hfx. volcanii ΔaglI cells grown in 3.4 M NaCl-containing growth medium modify DolP and S-layer glycoprotein Asn-498 with the low-salt tetrasaccharide. (A) In parent strain cells, no Asn-498-containing fragment from the S-layer glycoprotein of parent strain cells grown in high-salt medium modified by the low-salt tetrasaccharide was detected. (Inset) LC-ESI MS analysis of the low-salt tetrasaccharide-modified C₅₅ and C₆₀ dolichol phosphates in a total lipid extract of parent strain cells. (B) In ΔaglI cells, low-salt tetrasaccharide attached to Asn-498 is detected (lower). (Inset) LC-ESI MS analysis of a total lipid extract from ΔaglI cells reveals low-salt tetrasaccharide attached to C₅₅ and C₆₀ dolichol phosphates. The DolP-associated peaks shown in each upper panel correspond to [M-2H]²⁻ ions, while Asn-498 peptide-associated peaks shown in each lower panel correspond to [M + 2H]²⁺ ions. In each case, the lipid- or peptide-linked low-salt tetrasaccharide is schematically depicted at the indicated expected or observed position, with the open circle corresponding to rhamnose and the filled circles corresponding to hexose.