Catalyzes the GDP transfer from GTP to D-glycero-alpha-D-manno-heptose 1-phosphate, yielding GDP-D-alpha-D-heptose. Cannot use ATP, CTP, dTTP or UTP as substrate. D-glycero-alpha-D-manno-heptose 1-phosphate + GTP + H(+) = diphosphate + GDP-D-glycero-alpha-D-manno-heptose Nucleotide-sugar biosynthesis; GDP-D-glycero-alpha-D-manno-heptose biosynthesis; GDP-D-glycero-alpha-D-manno-heptose from D-glycero-alpha-D-manno-heptose 7-phosphate: step 3/3. Cell surface structure biogenesis; S-layer biogenesis. Belongs to the D-alpha-D-heptose-1-P guanylyltransferase family.